Alan Oppenheimer with several of the iconic characters he has voiced: Skeletor, Falkor, Man-At-Arms, and Mer-Man. Photo courtesy of Alan Oppenheimer. Alan Oppenheimer is one of the animation's most celebrated voice actors, having voiced Skeletor, Mer-Man, and Man-At-Arms on He-Man and the Masters of the Universe (1983-85), Vanity Smurf on The Smurfs (1981-89), Beachcomber and … Continue reading OH, CONTRARE! Alan Oppenheimer on His Legendary Acting Career and ‘Gammera the Invincible’!