Though he is also known for his appearances in several 1980s Bell Canada commercials and for his television roles in Here's Duffy, Accidental Family, and other series, Mann is perhaps best remembered for voicing Yukon Cornelius in the 1964 television special Rudolph the Red-Nosed Reindeer.
Before making his first television appearance in the 1954 CBC series Ad and Lib, Mann worked as a DJ for a Toronto radio station.
His film credits include roles in In the Heat of the Night and The Sting.
He grew up in Toronto, Ontario, Canada. His brother, Paul Mann, had a career as a film actor.
He got his start in the entertainment business after being noticed by producer Norman Jewison.