José de Acosta (1539–1600) – Jesuit missionary and naturalist who wrote one of the very first detailed and realistic descriptions of the new world
François d'Aguilon (1567–1617) – Belgian Jesuit mathematician, physicist, and architect.
Albert of Saxony (philosopher) (c. 1320–1390) – German bishop known for his contributions to logic and physics; with Buridan he helped develop the theory that was a precursor to the modern theory of inertia
Albertus Magnus (c. 1206–1280) – "One of the most famous precursors of modern science in the High Middles Ages."  Patron saint of natural sciences; Works in physics, logic, metaphysics, biology, and psychology.
José María Algué (1856–1930) – Meteorologist who invented the barocyclonometer
José Antonio de Alzate y Ramírez (1737–1799) – Scientist, historian, cartographer, meteorologist; wrote more than thirty treatises on a variety of scientific subjects
Francesco Castracane degli Antelminelli (1817–1899) – Botanist who was one of the first to introduce microphotography into the study of biology
Giovanni Antonelli (1818–1872) – Director of the Ximenian Observatory of Florence; collaborated on the design of a prototype of the internal combustion engine
Nicolò Arrighetti (1709–1767) – Wrote treatises on light, heat, and electricity.
Giuseppe Asclepi (1706–1776) – Astronomer and physician; director of the Collegio Romano observatory; The lunar crater Asclepi is named after him.
Roger Bacon (c. 1214–1294) – Significant contributions to mathematics and optics; forerunner of modern scientific method.
Bernardino Baldi (1533–1617) – Mathematician and writer
Eugenio Barsanti (1821–1864) – Possible inventor of the internal combustion engine
Bartholomeus Amicus (1562–1649) – Wrote on philosophy, mathematics, astronomy, and the concept of vacuum and its relationship with God.
Daniello Bartoli (1608–1685) – Bartoli and fellow Jesuit astronomer Niccolò Zucchi are credited as probably having been the first to see the equatorial belts on the planet Jupiter
Joseph Bayma (1816–1892) – Known for work in stereochemistry and mathematics
Giacopo Belgrado (1704–1789) – Experimental works in physics, professor of mathematics and physics, and court mathematician
Mario Bettinus (1582–1657) – Jesuit philosopher, mathematician and astronomer; lunar crater Bettinus named after him
Giuseppe Biancani (1566–1624) – Jesuit astronomer, mathematician, and selenographer, after whom the crater Blancanus on the Moon is named
Jacques de Billy (1602–1679) – Produced a number of results in number theory which have been named after him; published several astronomical tables; The crater Billy on the Moon is named after him.
Paolo Boccone (1633–1704) – Cistercian botanist who contributed to the fields of medicine and toxicology
Bernard Bolzano (1781–1848) – Mathematician and logician; other interests included metaphysics, ideas, sensation, and truth.
Anselmus de Boodt (1550–1632) – One of the founders of mineralogy
Theodoric Borgognoni (1205–1298) – Medieval Surgeon who made important contributions to antiseptic practice and anaesthetics
Christopher Borrus (1583–1632) – Mathematician and astronomy who made observations on the magnetic variation of the compass
Roger Joseph Boscovich (1711–1787) – formulation of modern atomic theory, important contributions to astronomy
Joachim Bouvet (1656–1730) – Jesuit sinologist and cartographer who did his work in China
Michał Boym (c. 1612–1659) – One of the first westerners to travel within the Chinese mainland, and the author of numerous works on Asian fauna, flora and geography.
Thomas Bradwardine (c. 1290–1349) – Mathematician who contributed to mean speed theorem; one of the Oxford Calculators
Henri Breuil (1877–1961) – Archaeologist, anthropologist, ethnologist and geologist.
Jan Brożek (1585–1652) – Polish polymath, mathematician, astronomer, and physician; the most prominent Polish mathematician of the 17th century
Louis-Ovide Brunet (1826–1876) – One of the founding fathers of Canadian botany
Francesco Faà di Bruno (c. 1825–1888) – Mathematician beatified by Pope John Paul II
Giordano Bruno (1548–1600) – Dominican philosopher, mathematician, and astronomer who believed in the infinity of the universe; burned at the stake for other heretical views.
Ismaël Bullialdus (1605–1694) – Astronomer and member of the Royal Society; the Bullialdus crater is named in his honor
Jean Buridan (c. 1300 – after 1358) – Early ideas of momentum and inertial motion; sowed the seeds of the Copernican revolution in Europe
Niccolò Cabeo (1586–1650) – Jesuit mathematician; the crater Cabeus is named in his honor
Nicholas Callan (1799–1846) – Best known for his work on the induction coil
Jean Baptiste Carnoy (1836–1899) – Founder of the science of cytology
Giovanni di Casali (died c. 1375) – Provided a graphical analysis of the motion of accelerated bodies
Paolo Casati (1617–1707) – Jesuit mathematician who wrote on astronomy and vacuums; The crater Casatus on the Moon is named after him.
Laurent Cassegrain (1629–1693) – Probable namesake of the Cassegrain telescope; The crater Cassegrain on the Moon is named after him
Benedetto Castelli (1578–1643) – Benedictine mathematician; long-time friend and supporter of Galileo Galilei, who was his teacher; wrote an important work on fluids in motion
Bonaventura Cavalieri (1598–1647) – He is known for his work on the problems of optics and motion, work on the precursors of infinitesimal calculus, and the introduction of logarithms to Italy. Cavalieri's principle in geometry partially anticipated integral calculus; the lunar crater Cavalerius is named in his honor
Antonio José Cavanilles (1745–1804) – A leading Spanish taxonomic botanist of the 18th century
Francesco Cetti (1726–1778) – Jesuit zoologist and mathematician
Tommaso Ceva (1648–1737) – Jesuit mathematician and professor who wrote treatises on geometry, gravity, and arithmetic
Christopher Clavius (1538–1612) – Respected Jesuit Astronomer and mathematician who headed the commission that yielded the Gregorian calendar; wrote influential astronomical textbook.
Guy Consolmagno (1952– ) – Jesuit astronomer and planetary scientist
Nicolaus Copernicus (1473–1543) –Renaissance astronomer famous for his heliocentric cosmology that set in motion the Copernican Revolution
Vincenzo Coronelli (1650–1718) – Franciscan cosmographer, cartographer, encyclopedist, and globe-maker
George Coyne (1933– ) – Jesuit astronomer and former director of the Vatican Observatory
James Cullen (mathematician) (1867–1933) – Jesuit mathematician who published what is now known as Cullen numbers in number theory
James Curley (astronomer) (1796–1889) – First director of Georgetown Observatory; determined the latitude and longitude of Washington D.C.
Albert Curtz (1600–1671) – Jesuit astronomer who expanded on the works of Tycho Brahe and contributed to early understanding of the moon; The crater Curtius on the Moon is named after him.
Johann Baptist Cysat (1587–1657) – Jesuit mathematician and astronomer, after whom the lunar crater Cysatus is named; published the first printed European book concerning Japan; one of the first to make use of the newly developed telescope; most important work was on comets
Ignazio Danti (1536–1586) – Dominican mathematician, astronomer, cosmographer, and cartographer
Armand David (1826–1900) – Zoologist and botanist who did important work in both areas in China
Charles-Michel de l'Épée (1712–1789) – Known as the "father of the deaf" and established the world's first free school for the deaf
Francesco Denza (1834–1894) – Meteorologist, astronomer, and director of Vatican Observatory
Václav Prokop Diviš (1698–1765) – Studied the lightning rod independent of Franklin; constructed the first electrified musical instrument in history
Johann Dzierzon (1811–1906) – Pioneering apiarist who discovered the phenomenon of parthenogenesis among bees, and designed the first successful movable-frame beehive; has been described as the "father of modern apiculture"
Honoré Fabri (1607–1688) – Jesuit mathematician and physicist
Jean-Charles de la Faille (1597–1652) – Jesuit mathematician who determined the center of gravity of the sector of a circle for the first time
Gabriele Falloppio (1523–1562) – One of the most important anatomists and physicians of the sixteenth century. The Fallopian tubes, which extend from the uterus to the ovaries, are named for him.
Gyula Fényi (1845–1927) – Jesuit astronomer and director of the Haynald Observatory; noted for his observations of the sun; The crater Fényi on the Moon is named after him
Louis Feuillée (1660–1732) – Explorer, astronomer, geographer, and botanist
Placidus Fixlmillner (1721–1791) – Benedictine priest and the first astronomer to compute the orbit of Uranus
Paolo Frisi (1728–1784) – Mathematician and astronomer who did significant work in hydraulics
José Gabriel Funes (1963– ) – Jesuit astronomer and current director of the Vatican Observatory
Joseph Galien (1699 – c. 1762) – Dominican professor who wrote on aeronautics, hailstorms, and airships
Jean Gallois (1632–1707) – French scholar and member of Academie des sciences
Pierre Gassendi (1592–1655) – French astronomer and mathematician who published the first data on the transit of Mercury; best known intellectual project attempted to reconcile Epicurean atomism with Christianity
Agostino Gemelli (1878–1959) – Franciscan physician and psychologist; founded Catholic University of the Sacred Heart in Milan
Johannes von Gmunden (c. 1380–1442) – Mathematician and astronomer who compiled astronomical tables; Asteroid 15955 Johannesgmunden named in his honor
Carlos de Sigüenza y Góngora (1645–1700) – Polymath, mathematician, astronomer, and cartographer; drew the first map of all of New Spain
Andrew Gordon (Benedictine) (1712–1751) – Benedictine monk, physicist, and inventor who made the first electric motor
Christoph Grienberger (1561–1636) – Jesuit astronomer after whom the crater Gruemberger on the Moon is named; verified Galileo's discovery of Jupiter's moons.
Francesco Maria Grimaldi (1618–1663) – Discovered the diffraction of light, and indeed coined the term "diffraction"; investigated the free fall of objects; built and used instruments to measure geological features on the moon
Robert Grosseteste (c. 1175 – 1253) – One of the most knowledgeable men of the Middle Ages; has been called "the first man to write down a complete set of steps for performing a scientific experiment." 
Paul Guldin (1577–1643) – Jesuit mathematician and astronomer who discovered the Guldinus theorem to determine the surface and the volume of a solid of revolution
Bartolomeu de Gusmão (1685–1724) – Known for his early work on lighter-than-air airship design
Johann Georg Hagen (1847–1930) – Director of the Georgetown and Vatican Observatories; The crater Hagen on the Moon is named after him.
Nicholas Halma (1755–1828) – French mathematician and translator
Jean-Baptiste du Hamel (1624–1706) – French natural philosopher and secretary of the Academie Royale des Sciences
René Just Haüy (1743–1822) – Father of crystallography
Maximilian Hell (1720–1792) – Jesuit astronomer and director of the Vienna Observatory; the crater Hell on the Moon is named after him.
Michał Heller (1936– ) – Templeton Prize winner and prolific writer on numerous scientific topics
Lorenz Hengler (1806–1858) – Often credited as the inventor of the horizontal pendulum
Hermann of Reichenau (1013–1054) – Historian, music theorist, astronomer, and mathematician
Pierre Marie Heude (1836–1902) – Jesuit missionary and zoologist who studied the natural history of Eastern Asia
Franz von Paula Hladnik (1773–1844) – Botanist who discovered several new kinds of plants, and certain genera have been named after him
Giovanni Battista Hodierna (1597–1660) – Astronomer who catalogued nebulous objects and developed an early microscope
Victor-Alphonse Huard (1853–1929) – Naturalist, educator, writer, and promoter of the natural sciences
Maximus von Imhof (1758–1817) – German Augustinian physicist and director of the Munich Academy of Sciences
Giovanni Inghirami (1779–1851) – Italian astronomer; there is a valley on the moon named after him as well as a crater
François Jacquier (1711–1788) – Franciscan mathematician and physicist; at his death he was connected with nearly all the great scientific and literary societies of Europe
Stanley Jaki (1924–2009) – Benedictine priest and prolific writer who wrote on the relationship between science and theology
Ányos Jedlik (1800–1895) – Benedictine engineer, physicist, and inventor; considered by Hungarians and Slovaks to be the unsung father of the dynamo and electric motor
Georg Joseph Kamel (1661–1706) – Jesuit missionary and botanist who established the first pharmacy in the Philippines
Otto Kippes (1905–1994) – Acknowledged for his work in asteroid orbit calculations; the main belt asteroid 1780 Kippes was named in his honour
Athanasius Kircher (1602–1680) – The father of Egyptology; "Master of a hundred arts"; wrote an encyclopedia of China; one of the first people to observe microbes through a microscope
Wenceslas Pantaleon Kirwitzer (1588–1626) – Jesuit astronomer and missionary who published observations of comets
Jan Krzysztof Kluk (1739–1796) – Naturalist agronomist and entomologist who wrote a multi-volume work on Polish animal life
Sebastian Kneipp (1821–1897) – One of the founders of the Naturopathic medicine movement
Marian Wolfgang Koller (1792–1866) – Professor who wrote on astronomy, physics, and meteorology
Franz Xaver Kugler (1862–1929) – Jesuit chemist, mathematician, and Assyriologist who is most noted for his studies of cuneiform tablets and Babylonian astronomy
Eugene Lafont (1837–1908) – Jesuit physicist, astronomer, and founder of the first Scientific Society in India
Antoine de Laloubère (1600–1664) – The first mathematician to study the properties of the helix
Bernard Lamy (1640–1715) – Philosopher and mathematician who wrote on the parallelogram of forces
Pierre André Latreille (1762–1833) – Entomologist whose works describing insects assigned many of the insect taxa still in use today
Georges Lemaître (1894–1966) – Father of the Big Bang Theory
Thomas Linacre (c. 1460–1524) – Humanist translator and physician
Francis Line (1595–1675) – Magnetic clock and sundial maker who disagreed with some of the findings of Newton and Boyle
Juan Caramuel y Lobkowitz (1606–1682) – Prolific writer on a variety of scientific subjects; a earlier writer on probability
Jean Mabillon (1632–1707) – Benedictine monk and scholar, considered the founder of palaeography and diplomatics
James B. Macelwane (1883–1956) – "The best-known Jesuit seismologist" and "one of the most honored practicioners of the science of all time"; wrote the first textbook on seismology in America.
Paul McNally (1890–1955) – Jesuit astronomer and director of Georgetown Observatory; the crater McNally on the Moon is named after him.
Pierre Macq (1930– ) – Physicist who was awarded the Francqui Prize on Exact Sciences for his work on experimental nuclear physics
Manuel Magri (1851–1907) – Jesuit ethnographer, archaeologist and writer; one of Malta's pioneers in archaeology
Emmanuel Maignan (1601–1676) – Physicist and professor of medicine who published works on gnomonics and perspective
Charles Malapert (1581–1630) – Jesuit writer, astronomer, and proponent of Aristotelian cosmology; also known for observations of sunpots and of the lunar surface, and the crater Malapert on the Moon is named after him
Nicolas Malebranche (1638–1715) – Philosopher who studied physics, optics, and the laws of motion; disseminated the ideas of Descartes and Leibniz
Marcin of Urzędów (c. 1500–1573) – Physician, pharmacist, and botanist
Joseph Maréchal (1878–1944) – Jesuit philosopher and psychologist
Marie-Victorin (1885–1944) – Botanist best known as the father of the Jardin botanique de Montréal
Edme Mariotte (c. 1620–1684) – Physicist who recognized Boyle's Law and wrote about the nature of color
Francesco Maurolico (1494–1575) – Made contributions to the fields of geometry, optics, conics, mechanics, music, and astronomy; gave the first known proof by mathematical induction
Christian Mayer (astronomer) (1719–1783) – Jesuit astronomer most noted for pioneering the study of binary stars
Gregor Mendel (1822–1884) – Augustinian monk and father of genetics
Pietro Mengoli (1626–1686) – Mathematician who first posed the famous Basel Problem
Giuseppe Mercalli (1850–1914) – Volcanologist and director of the Vesuvius Observatory; best remembered today for his Mercalli scale for measuring earthquakes which is still in use
Marin Mersenne (1588–1648) – Philosopher, mathematician, and music theorist who is often referred to as the "father of acoustics"
Paul of Middelburg (1446–1534) – Wrote important works on the reform of the Calendar
Maciej Miechowita (1457–1523) – Wrote the first accurate geographical and ethnographical description of Eastern Europe; also wrote two medical treatises
François-Napoléon-Marie Moigno (1804–1884) – Jesuit physicist and mathematician; was an expositor of science and translator rather than an original investigator
Juan Ignacio Molina (1740–1829) – Jesuit naturalist, historian, botanist, ornithologist and geographer
Louis Moréri (1643–1680) – 17th century encyclopaedist
Théodore Moret (1602–1667) – Jesuit mathematician and author of the first mathematical dissertations ever defended in Prague; the lunar crater Moretus is named after him.
Landell de Moura (1861–1928) – Inventor who was the first to accomplish the transmission of the human voice by a wireless machine
Gabriel Mouton (1618–1694) – Mathematician, astronomer, and early proponent of the metric system
Jozef Murgaš (1864–1929) – Contributed to wireless telegraphy and help develop mobile communications and wireless transmission of information and human voice
José Celestino Mutis (1732–1808) – Botanist and mathematician who led the Royal Botanical Expedition of the New World
Antonio Neri (1576–1614) – Herbalist, alchemist, and glassmaker
Jean François Niceron (1613–1646) – Mathematician who studied geometrical optics
Nicholas of Cusa (1401–1464) – Cardinal, philosopher, jurist, mathematician, and astronomer; one of the great geniuses and polymaths of the 15th century
Julius Nieuwland (1878–1936) – Holy Cross priest, known for his contributions to acetylene research and its use as the basis for one type of synthetic rubber, which eventually led to the invention of neoprene by DuPont
Jean-Antoine Nollet (1700–1770) – Physicist who discovered the phenomenon of osmosis in natural membranes.
Hugo Obermaier (1877–1946) – Distinguished prehistorian and anthropologist who is known for his work on the diffusion of mankind in Europe during the Ice Age, and in connection with north Spanish cave art
William of Ockham (c. 1288 – c. 1348) – Franciscan Scholastic who wrote significant works on logic, physics, and theology; known for Ockham's Razor
Nicole Oresme (c. 1323–1382) – One of the most famous and influential philosophers of the later Middle Ages; economist, mathematician, physicist, astronomer, philosopher, theologian and Bishop of Lisieux, and competent translator; one of the most original thinkers of the 14th century
Barnaba Oriani (1752–1832) – Geodesist, astronomer and scientist; greatest achievement was his detailed research of the planet Uranus; known for Oriani's theorem
Luca Pacioli (c. 1446–1517) – Often regarded as the Father of Accounting; published several works on mathematics
Ignace-Gaston Pardies (1636–1673) – Physicist known for his correspondence with Newton and Descartes
Franciscus Patricius (1529–1597) – Cosmic theorist, philosopher, and Renaissance scholar
John Peckham (1230–1292) – Archbishop of Canterbury and early practitioner of experimental science
Nicolas Claude Fabri de Peiresc (1580–1637) – Astromer who discovered the Orion Nebula; lunar crater Peirescius named in his honor
Stephen Joseph Perry (1833–1889) – Jesuit astronomer and Fellow of the Royal Society; made frequent observations of Jupiter's satellites, of stellar occultations, of comets, of meteorites, of sun spots, and faculae
Giambattista Pianciani (1784–1862) – Jesuit mathematician and physicist
Giuseppe Piazzi (1746–1826) – Theatine mathematician and astronomer who discovered Ceres, today known as the largest member of the asteroid belt; also did important work cataloguing stars
Jean Picard (1620–1682) – First person to measure the size of the Earth to a reasonable degree of accuracy; also developed what became the standard method for measuring the right ascension of a celestial object; The PICARD mission, an orbiting solar observatory, is named in his honor
Edward Pigot (1858–1929) – Jesuit seismologist and astronomer
Alexandre Guy Pingré (1711–1796) – French astronomer and naval geographer; the crater Pingré on the Moon is named after him, as is the asteroid 12719 Pingré
Jean Baptiste François Pitra (1812–1889) – Bendedictine cardinal, archaeologist and theologian who noteworthy for his great archaeological discoveries
Charles Plumier (1646–1704) – Considered one of the most important botanical explorers of his time
Marcin Odlanicki Poczobutt (1728–1810) – Jesuit astronomer and mathematician; granted the title of the King's Astronomer; the crater Poczobutt on the Moon is named after him.
Léon Abel Provancher (1820–1892) – Naturalist devoted to the study and description of the fauna and flora of Canada; his pioneer work won for him the appellation of the "Father of Natural History in Canada"
Louis Receveur (1757–1788) – Franciscan naturalist and astronomer; described as being as close as one could get to being an ecologist in the 18th century
Franz Reinzer (1661–1708) – Wrote an in-depth meteorological, astrological, and political compendium covering topics such as comets, meteors, lightning, winds, fossils, metals, bodies of water, and subterranean treasures and secrets of the earth
Louis Rendu (1789–1859) – Bishop who wrote an important book on the mechanisms of glacial motion; the Rendu Glacier, Alaska, U.S. and Mount Rendu, Antarctica are named for him
Vincenzo Riccati (1707–1775) – Italian mathematician and physicist
Matteo Ricci (1552–1610) – One of the founding fathers of the Jesuit China Mission; co-author of the first European-Chinese dictionary
Giovanni Battista Riccioli (1598–1671) – Astronomer who authored Almagestum novum, an influential encyclopedia of astronomy; The first person to measure the rate of acceleration of a freely falling body; created a selenograph with Father Grimaldi that now adorns the entrance at the National Air and Space Museum in Washington D.C.
Johannes Ruysch (c. 1460–1533) – Explorer, cartographer, and astronomer who created the second oldest known printed representation of the New World
Giovanni Girolamo Saccheri (1667–1733) – Jesuit mathematician and geometer
Johannes de Sacrobosco (c. 1195 – c. 1256) – Irish monk and astronomer who wrote the authoritative medieval astronomy text Tractatus de Sphaera; his Algorismus was the first text to introduce Hindu-Arabic numerals and procedures into the European university curriculum; the lunar crater Sacrobosco is named after him
Gregoire de Saint-Vincent (1584–1667) – Jesuit mathematician who made important contributions to the study of the hyperbola
Alphonse Antonio de Sarasa (1618–1667) – Jesuit mathematician who contributed to the understanding of logarithms
Christoph Scheiner (c. 1573–1650) – Jesuit physicist, astronomer, and inventor of the pantograph; wrote on a wide range of scientific subjects
George Schoener (1864–1941) – Became known in the United States as the "Padre of the Roses" for his experiments in rose breeding
Gaspar Schott (1608–1666) – Jesuit physicist, astronomer, and natural philosopher who is most widely known for his works on hydraulic and mechanical instruments
Franz Paula von Schrank (1747–1835) – Botanist, entomologist, and prolific writer
Berthold Schwarz (c. 14th century) – Franciscan friar and reputed inventor of gunpowder and firearms
Anton Maria Schyrleus of Rheita (1604–1660) – Astronomer and optrician who built Kepler's telescope
George Mary Searle (1839–1918) – Paulist astronomer and professor who discovered six galaxies
Angelo Secchi (1818–1878) – Pioneer in astronomical spectroscopy, and was one of the first scientists to state authoritatively that the Sun is a star
Włodzimierz Sedlak (1911–1993) – Father of polish bioelectronics[clarification needed] and the electromagnetic theory of life[clarification needed]
Alessandro Serpieri (1823–1885) – Astronomer and seismologist who studied shooting stars, and was the first to introduce the concept of the seismic radiant
Gerolamo Sersale (1584–1654) – Jesuit astronomer and selenographer; his map of the moon can be seen in the Naval Observatory of San Fernando; the lunar crater Sirsalis is named after him
Benedict Sestini (1816–1890) – Jesuit astronomer, mathematician and architect; studied sunspots and eclipses; wrote textbooks on a variety of mathematical subjects
René François Walter de Sluse (1622–1685) – Mathematician with a family of curves named after him
Lazzaro Spallanzani (1729–1799) – Biologist and physiologist who made important contributions to the experimental study of bodily functions, animal reproduction, and essentially discovered echolocation; his research of biogenesis paved the way for the investigations of Louis Pasteur
Valentin Stansel (1621–1705) – Jesuit astronomer who made important observations of comets
Johan Stein (1871–1951) – Jesuit astronomer and director of the Vatican Observatory, which he modernized and relocated to Castel Gandolfo; the crater Stein on the far side of the Moon is named after him
Nicolas Steno (1638–1686) – Often called the father of geography and stratigraphy ("Steno's principles"); beatified by Pope John Paul II
Pope Sylvester II (c. 946–1003) – Prolific scholar who endorsed and promoted Arabic knowledge of arithmetic, mathematics, and astronomy in Europe, reintroducing the abacus and armillary sphere which had been lost to Europe since the end of the Greco-Roman era
Alexius Sylvius Polonus (1593 – c. 1653) – Jesuit astronomer who studied sunspots and published a work on calendariography
Ignacije Szentmartony (1718–1793) – Jesuit cartographer, mathematician, and astronomer who became a member of the expedition that worked on the rearrangement of the frontiers among colonies in South America
André Tacquet (1612–1660) – Jesuit mathematician whose work laid the groundwork for the eventual discovery of calculus
Pierre Teilhard de Chardin (1881–1955) – Jesuit paleontologist and geologist who took part in the discovery of Peking Man
Francesco Lana de Terzi (c. 1631–1687) – Referred to as the Father of Aeronautics for his pioneering efforts; also developed the idea that developed into Braille
Theodoric of Freiberg (c. 1250 – c. 1310) – Dominican theologian and physicist who gave the first correct geometrical analysis of the rainbow
Joseph Tiefenthaler (1710–1785) – One of the earliest European geographers to write about India
Giuseppe Toaldo (1719–1797) – Physicist who studied atmospheric electricity and did important work with lightnight rods; the asteroid 23685 Toaldo is named for him.
José Torrubia (c. 1700–1768) – Linguist, scientist, collector of fossils and books, and writer on historical, political and religious subjects
Franz de Paula Triesnecker (1745–1817) – Jesuit astronomer and director of the Vienna Observatory; published a number of treatises on astronomy and geography; the crater Triesnecker on the Moon is named after him.
Basil Valentine (c. 15th century) – Alchemist whom author James J. Walsh calls the father of modern chemistry 
Luca Valerio (1552–1618) – Jesuit mathematician who developed ways to find volumes and centers of gravity of solid bodies
Pierre Varignon (1654–1722) – Mathematician whose principle contributions were to statics and mechanics; created a mechanical explanation of gravitation
Fausto Veranzio (c. 1551–1617) – Bishop, polymath, inventor, and lexicographer
Ferdinand Verbiest (1623–1688) – Jesuit astronomer and mathematician; designed what some claim to be the first ever self-propelled vehicle – many claim this as the world's first automobile
Francesco de Vico (1805–1848) – Jesuit astronomer who discovered or co-discovered a number of comets; also made observations of Saturn and the gaps in its rings; the lunar crater De Vico and the asteroid 20103 de Vico are named after him
Vincent of Beauvais (c.1190–c.1264) – Wrote the most influential encyclopedia of the Middle Ages
János Vitéz (archbishop) (c.1405–1472) – Archbishop, astronomer, and mathematician
Martin Waldseemüller (c. 1470–1520) – German cartographer who, along with Matthias Ringmann, is credited with the first recorded usage of the word America
Godefroy Wendelin (1580–1667) – Astronomer who recognized that Kepler's third law applied to the satellites of Jupiter; the lunar crate Vendelinus is named in his honor
Johannes Werner (1468–1522) – Mathematician, astronomer, and geographer
Witelo (c. 1230 – after 1280, before 1314) – Physicist, natural philosopher, and mathematician; lunar crater Vitello named in his honor; his Perspectiva powerfully influenced later scientists, in particular Johannes Kepler
Julian Tenison Woods (1832–1889) – Passionist geologist and mineralogist
Theodor Wulf (1868–1946) – Jesuit physicist who was one of the first experimenters to detect excess atmospheric radiation
John Zahm (1851–1921) – Holy Cross Priest and South American explorer
Giuseppe Zamboni (1776–1846) – Physicist who invented the Zamboni pile, an early electric battery similar to the Voltaic pile
Francesco Zantedeschi (1797–1873) – Among the first to recognize the marked absorption by the atmosphere of red, yellow, and green light; published papers on the production of electric currents in closed circuits by the approach and withdrawal of a magnet, thereby anticipating Michael Faraday's classical experiments of 1831
Niccolò Zucchi (1586–1670) – Attempted to build a reflecting telescope in 1616; may have been the first to see the belts on the planet Jupiter; corresponded with Kepler
Giovanni Battista Zupi (c. 1590–1650) – Jesuit astronomer, mathematician, and first person to discover that the planet Mercury had orbital phases; the crater Zupus on the Moon is named after him