Morrison portrayed the Shadow longer than any other actor, spending ten years in the role in two separate runs. Bill Johnstone played the Shadow until early 1943. Morrison replaced Johnstone in April, 1943, continuing until 1944. John Archer (1944-45) was followed by Steve Courtleigh (1945). Morrison then returned from 1945 until 1954. For many, he was the definitive voice of the Shadow, though his delivery was much less sinister–and, some would say, less compelling–than Orson Welles, who also portrayed the Shadow.
At age 66, Morrison died of a heart attack. He was found slumped over the steering wheel of his parked car on a Hollywood street where he had stopped for shopping after taping an episode of Heartbeat Theater. It was believed 107-degree temperatures in a Southern California heat wave may have prompted Morrison's heart attack.