Donald James Henderson (August 7, 1940 – May 2, 2020) was a Canadian politician, who served as a Liberal member of the Legislative Assembly of Ontario from 1985 to 1995.
He worked as a physician, psychiatrist, psychoanalyst, Director of Psychiatry at the Lakeshore Psychiatric Hospital in Toronto and the Royal Victoria Hospital in Barrie before entering political life, and served as an associate professor in the Department of Psychiatry, and Psychiatrist in Chief for the Student Health Services, at the University of Toronto.
Henderson states that his decision to enter politics was as simple as stepping off the street car and saying "I want to be a candidate" at the Liberal constituency office for the riding.
The Liberals were upset by the New Democratic Party in the 1990 provincial election, although Henderson managed to defeat his NDP opponent by about 3,500 votes.
In another, which received first reading in 1987, would have allowed individuals to request anonymous HIV testing by amending the mandatory reporting requirements in the Health Protection and Promotion Act.