Updated: October 12, 2025

The TV show Lost in Space featured numerous "Monsters," including a variety of aliens, mutated creatures, and other strange beings. Some of the most memorable include the cyclops, the bubble creatures, the space creature from a possessed Dr. Smith, and a giant, mutant "Attack of the Monster Plants". Many costumes were recycled between Lost in Space and other Irwin Allen shows, like Voyage to the Bottom of the Sea, to create these creatures.

Memorable Monsters:

Cyclops: A large, imposing creature from the early episodes.

Bubble Creatures: Bipedal aliens with pulsating, bubble-like protrusions on their bodies that communicated through electrical arcs.

Space Creature: An entity that possessed Dr. Smith, appearing as a shadowy, mist-like figure that took on the form of a future Will Robinson before being destroyed.

Attack of the Monster Plants: Giant, carnivorous plants that grew from a spill of deutronium, which also created a vegetable clone of Judy.

Bog Monster: A creature from a radioactive swamp, encountered by the Robinson family in the "Ghost in Space" episode.

Mossman: A green-skinned creature with glowing amber eyes from the episode "The Android Machine".

Mummy-like creature: A frightening, featureless creature from the episode "Wish Upon a Star".