The first of the three Capsule Monsters used by Ultraseven, Windom was a metallic giant life form from Planet Metal with an electronic brain. It was first used to fight an Alien Cool's saucer fleet and managed to destroy a few saucers, but the saucers started to fire their beams, forcing Dan to summon him back.

Windom reappeared to fight the Alien Cannan's ship (which was disguised as a lighthouse). As Windom approached it, he was struck by two beams that brainwashed him into attacking Dan. Ultraseven fought Windom and broke the hypnotic spell by firing a weaker version of the Emerium Beam. Once freed, Windom tried to attack the base again, but was hit by another ray that made him fall unconscious, forcing Ultraseven to recall him again.

Windom was used for the last time against Alien Guts. After Guts fooled around with his teleporting, he summoned his saucer that fired a beam that engulfed Windom in flames, killing the capsule monster, never to be used again during Seven's stay on Earth.