Before he took helm of the U.S.S. Enterprise in 1966, William Shatner appeared in one of the decade’s other great sci-fi TV series: The Twilight Zone. The more memorable of his two appearances came in the episode “Nightmare at 20,000 Feet” (itself one of the series’ most famous), in which he stars as a man on a flight menaced by a large destructive gremlin. Directed by Richard Donner (who would later go on to helm the first Superman film and the Lethal Weapon movies), “Nightmare” shows Shatner — playing a character recovering from a mental breakdown — at his jittery finest. Though the distinctive verbal style that would later be so easily mockable pops up here, it is easily overshadowed by Shatner’s sweaty performance.