 He voiced the character of Merlin in Walt Disney's 1963 animated classic, "The Sword in the Stone".In 1969, he was cast as the Roman emperor Nero, sent by the Devil to assassinate Santa Claus in a KCET television reading of Norman Corwin's 1938 radio play "The Plot to Overthrow Christmas".Swenson appeared in a 1967 episode of "Hogan's Heroes" entitled "How to Win Friends and Influence Nazis", in which he played a likable and friendly Swedish scientist, Dr. Karl Svenson, who is persuaded by Hogan (Bob Crane) to join the Allied war effort.