Martin Chalfie (born January 15, 1947) is an American scientist. He shared the 2008 Nobel Prize in Chemistry along with Osamu Shimomura and Roger Y. Tsien "for the discovery and development of the green fluorescent protein, GFP".

He holds a Ph.D. in neurobiology from Harvard University.
In the summer of 1971, his research at the laboratory of Jose Zadunaisky at Yale University resulted in his first publication. With revived confidence, he returned to Harvard for graduate studies under Robert Perlman, and received his Ph.D. in 1977.
He conducted his postdoctoral research at the LMB with Sidney Brenner and John Sulston, and the three published a paper in 1985 on "The Neural Circuit for Touch Sensitivity in C. elegans". Chalfie then left the LMB in 1982 to join the faculty of Columbia University in the department of biological sciences and continued to study C. elegans touch mutants.
Chalfie and his wife had a daughter, Sarah, in July of 1992.
Chalfie was elected to the National Academy of Sciences in 2004.