Lost in Space (1965)

Season 3: Episode 10

A strange blue fog seems to be engulfing the Jupiter 2 periodically. Dr Smith and Will commment seperately that they want to be left alone. When the members of the Jupiter 2 begin to randomly disappear as the fog comes, Dr Smith thinks he is to blame. Eventually Will discovers a strange creature which takes over Dr Smith. The creature tells Will that he is his own Id. Will finds out his Id is a creature he created full of Will's own personal demons, thoughts, feelings and insecurities. Will defeats the creature by overcoming his ""fears"" and throws the powerless creature in the power core. The members of his family are returned.