Kenneth Mars. Actor: Frankenstein Junior. Kenneth Mars was an American actor and comedian. He appeared in two Mel Brooks films: as the deranged Nazi playwright Franz Liebkind in The Producers (1967) and Police Inspector Hans Wilhelm Friedrich Kemp in Young Frankenstein (1974). He also appeared in Peter Bogdanovich's What's Up Doc? (1972), and Woody Allen's Radio Days (1987), and Shadows and Fog (1991).