Jean'ne Marie Shreeve born 1933: synthetic fluorine chemistry, particularly fluorinated compounds of nitrogen, sulfur, and phosphorus; Garvan Medal, 1972.
Camillo Golgi born 1843: neuroscience, including the so-called "black reaction" for staining nerve cells; Nobel Prize (Medicine), 1906. (Thanks to Ray Williams at ACS for pointing me toward this entry.)
Jason Cardelli reported in Science interstellar abundances of the heaviest elements yet detected in interstellar gas (including thallium and lead), 1994.
Heinz Fraenkel-Conrat born 1910: separated viral RNA from protein and showed that RNA was the active agent, turning attention to the role of nucleic acids in heredity.