Aliens do not appear in five out of the 24 episodes making up the third season of Lost in Space, but the remaining episodes more than make up for this in the sheer number of aliens seen in season three. “A Day at the Zoo,” “Two Weeks in Space,” and “Space Beauty” portray several races each, although most are only seen and have no dialogue. Four episodes are notable for the conflict being caused by a single alien. This is J-5 in “The Haunted Lighthouse,” Will’s alter-ego in “Space Creature,” the Time Merchant in the episode of the same name, and Anti-John in “The Anti-Matter Man.”