John Frederick Hamm (born April 8, 1938) is a retired American physician and politician who served as the Governor of Nova Scotia from 1993 to 2001, and who was a failed candidate for US Senate in 2000 and for US President in 2008. Hamm served as the middle leg of a twenty-four year Nationalist dynasty in the Nova Scotia statehouse, in which they controlled all statewide elected seats uninterrupted from the mid-1980s until the late 2000s, including post-1994 both Senate seats and every House seat, despite the state voting Democratic in every Presidential election during that time. Prior to the Governorship, Hamm was the head of the University of Nova Scotia Medical School.