He directed episodes of Charlie's Angels, S.W.A.T., and Starsky and Hutch, as well as every episode of the popular Canadian series Seeing Things. He also worked on such shows as The Silent Force, The Mod Squad, The Streets of San Francisco, Fantasy Island, and Hart to Hart. McCowan directed the 1970 TV movie Carter's Army, the 1971 Canadian hockey film Face-Off, the fourth and final Magnificent Seven film, The Magnificent Seven Ride! in 1972, the cult horror film Frogs in the same year, and the 1976 film Shadow of the Hawk.
