|Behind the scenes|
Gallaxhar is the main antagonist of the film. He is the leader of the invading alien force trying to take over Earth.
Gallaxhar is awoken from his cryogenic sleep when his computer detects Quantonium. Gallaxhar then sends a gigantic Robot Probe to extract and bring it to him. When the monsters defeat his probe, he almost sends another probe, but his computer tells him that the "carbon-based lifeform" (Ginormica) is now too strong, and that the Quantonium can not be retrieved by a Robot. He comes to Earth and sends a message to the citizens of Earth, then captures Ginormica, and in the process blasts Insectosaurus with his ship's phasoid cannon. When Ginormica is on board the ship, she frees herself, and Gallaxhar then flees to his Extraction Chamber, where he gets the Quantonium out of Ginormica. He succeeds and clones himself four times. This is enough for him to create an evil clone army of himself. After Dr. Cockroach destroys his computer by stepping on the color buttons in the correct order while dancing, the self destruct system sounds. He attempts to escape, but is once again forced into combat with Ginormica. She then gets her Quantonium back and escapes on Insectosaurus (who is now a butterfly). Gallaxhar tries to escape in an escape-pod, but fails and presumably dies in the explosion.
He is voiced by Rainn Wilson. He was one of the few villains not to be resurrected by Simon West. Gallaxhar was briefly mentioned by Coverton in the first episode of the TV Series, Welcome to Area Fifty-Something