The Giant Cyclops is a roughly 18 meters tall one-eyed humanoid native to the canyons of planet Preplanis.
Its behavior is distinctly hostile, even towards much smaller beings that couldn't possibly represent a threat to it, indicating predatory habits. It also shows signs of some level of advanced intellect, such as throwing boulders at its targets.
It's likely that this species became extinct after the destruction of Preplanis.
- Lost in Space, s01e04, "There Were Giants in the Earth" (1965)
- Human-sized individuals of this species have been observed among the creatures owned by the Keeper, indicating that the Giant Cyclops might have been, in fact, an abnormal member of its species; having grown to giant size perhaps as a result of eating the same fruit eaten by Dr. Smith and Debbie in "The Oasis".
- In the third season episode "Flight to the Future", footage of the Cyclops is shown as one of the illusions haunting Will Robinson, Dr. Smith, and the Robot, as they're stranded on an alien planet.