Frances Kathleen Oldham Kelsey, Ph.D., M.D. (1914–2015), was a naturalized American pharmacologist, most famous as the reviewer for the U.S. Food and Drug Administration (FDA) who refused to authorize thalidomide for market because she had concerns about the drug's safety. Her concerns proved to be justified when it was proven that thalidomide caused birth defects. Kelsey's career intersected with the passage of laws strengthening the FDA's oversight of pharmaceuticals.