Important scientists

 

A

 Edgar Adrian (1889 - 1977)  physiologist  neuron function, neurophysiology (with Sherrington)
 Louis Agassiz (1807 - 1873)  paleontologist  fossil fish, glaciers and ice ages
 Peter Agre (1949 - )  biochemist  ion channels, aquaporins, cell membrane (with MacKinnon)
 Georgius Agricola      see Georg Pawer
 Yakir Aharonov (1932 - )  physicist  quantum mechanics, Aharonov-Bohm effect
 Kurt Alder (1902 - 1958)  chemist  Diels-Alder reaction, cycloaddition (with Diels)
 Alexei Abrikosov ((1928 - )  physicist  condensed matter physics, superconductivity, superfluidity (with Ginsburg, Leggett)
 Zhores Alferov (1930 - )  physicist  semiconductor devices, optoelectronics (with Kroemer)
 Hannes Alfven (1908 - 1995) physicist  solid-state physics, magnetism, (with Nel)
 Sidney Altman (1939 - )  biochemist  tRNA catalysis*, ribozymes (with Cech)
 Luis Alvarez (1911 - 1988)  physicist  radar, thermal neutrons
 Walter Alvarez (1940 - )  physicist  dinosaur extinction dating
 Andre-Marie Ampre (1775 - 1836)  physicist  discovered electromagnetism
 Carl Anderson (1905 - 1991)  physicist  discovered positron and muon
 Philip Anderson (1923 - )  physicist  superconductivity, Anderson localization, amorphous solids (with Mott, van Vleck)
 Christian Anfinsen (1916 - 1995)  biochemist  ribonuclease, Anfinsen's dogma (with Moore, Stein)
 Mary Anning (1799 - 1847)  fossil collector  first ichthyosaur and plesiosaur fossils

 Nicolas Appert

(1750 - 1841)  confectioner  invented canning process for food preservation
 Edward Appleton (1892 - 1965)  physicist  ionosphere, radio waves reflection
 Werner Arber (1929 - )  geneticist  restriction endonucleases (with Nathans, Smith)

 Archimedes

(287 - 212 BC)  mathematician  Archimedes screw water pump; determined π (pi)

 Richard Armstrong

(1937 - 1991)  geologist  radiometric dating

 Svante Arrhenius

(1859 - 1927)  physical chemist  Arrhenius equation, climate change
 Francis Aston (1877 - 1945)  physicist  Aston dark space, mass spectrometer, whole number rule

 David Attenborough

(1926 - )  naturalist  Life nature TV series; see own website

 John Audobon

(1785 - 1851)  naturalist  bird species (see Audobon Society)

 Oswald Avery

(1877 - 1955)  biochemist  DNA is genes and chromosomes

 Amedeo Avogadro

(1776 - 1856)  theorist  Avogadro's Law of molecules, molecular theory
 David Awschalom (?)  physicist  spintronics in semiconductors
 Richard Axel (1946 - )  neuroscientist  olfactory receptors, G-protein coupled receptors (with Buck)
 Julius Axelrod (1912 - 2004)  biochemist  neurotransmitters, epinephrine, norepinephrine (with von Euler, Katz)
      *  no Wikipedia reference for this technique - search on Google