John C. "Jock" Chisholm ( 1896 – July 4, 1958) was the first chief constable of the Toronto Police Department and Metropolitan Toronto Police Force until his death in 1958. Chisholm was the first Toronto chief to be appointed with policing experience.
Chisholm's father was a lay preacher in Dundee City Prison when John was growing up, giving him an interest in criminology. He was educated at the High School of Dundee.
He served in World War I with the artillery in Mesopotamia (modern Iraq) and, after the war, decided to enter policing. After finding no openings with the Hong Kong Police, he came to Canada where he joined the Toronto Police Department in 1920 he became an acting detective in three years, skipped a rank, to become detective sergeant in 1930 and went on to become the youngest inspector and then youngest deputy chief in the department's history in 1945 before becoming chief constable on the Cit