Born in the small South Dakota city of Mitchell, Carlson earned both a BFA and an MA from the University of South Dakota, which he attended in the 1950s and began his acting career performing in several stage plays in both the U.S and England. His performances include A Walk in the Woods in 1991 at the Gateway Theatre and Glengarry Glen Ross, Jekyll & Hyde (musical), Hamlet, Joggers, All My Sons, and Death and the Maiden. He immigrated to Canada in the late 1960s and began acting in many films and TV shows in the early '70s. His most memorable film roles were in the horror classic Black Christmas and Deranged, both in 1974. Carlson appeared in four movies from Director David Cronenberg, including Videodrome and The Dead Zone. His TV appearances include The X-Files, Friday the 13th: The Series, 21 Jump Street and Road to Avonlea.
Carlson was married to Actress Patricia Hamilton, and they had one child together, actor Ben Carlson. He had another son, Edmund Carlson, with his second wife, Joan Warren, in 1988. He died of cancer in Toronto, Ontario.