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.

Nicolas Louis de Lacaille (1713-1762) – French astronomer noted for cataloguing stars, nebulous objects, and constellations.

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.

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..

Richard of Wallingford (1292-1336) - Renowned clockmaker and one of the initiators of Western Trigonometry.

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.

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 lightning 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 [8].

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.

Giovanni Battista Venturi (1746-1822) - Discovered the Venturi effect.
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.

Franz Xaver von Wulfen (1728-1805) - Jesuit botanist, minerologist, and alpinist.
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.