Thressa Campbell Stadtman (February 12, 1920 – December 11, 2016) was an American biochemist, notable for her discovery of selenocysteine,[2] and her research on selenoproteins and bioenergetics.

In addition she made significant advances in amino acid metabolism, enzymes dependent on vitamin B12, and the biochemistry of microbes.

In 1949, she graduated from University of California, Berkeley, with a Ph.D. in Microbial Biochemistry.

Her thesis was titled "Studies on Methane Fermentations", and subsequently worked as a postdoc for Christian B. Anfinsen.

She was married to Earl Reece Stadtman whom she met when they were both graduate students at the University of California, Berkeley.