Our 2nd You Know The Voice entry today showcases one of our favorites, Casey Kasem.
If you thought Casey only got to impersonate Columbo on The Dean Martin Celebrity Roast, well, you thought wrong! Musician-turned-producer Glen A. Larson caught Casey's act in the roast of Telly Savalas, and cast the King of the Countdowns in a 2-part Hardy Boys-Nancy Drew Mysteries episode, broadcast in October 1977. Casey dons that rumpled raincoat again, but the only complaint folks seem to have is that he didn't completely impersonate Peter Falk. He only had the hand gestures down, and knew how to stoop down just enough to effect the look.
Here's "The Mystery of the Hollywood Phantom", also at The Land of Whatever.
Edit, 11/15/16: The original 2-part video has been deleted due to copyright issues. I've replaced it with this excerpt: