Gallaxhar is the main antagonist of the film, Monsters vs. Aliens. He is the leader of the invading alien force trying to take over Earth. He was awoken from his cryogenic sleep when his computer detected Quantonium. Gallaxhar then sent a Robot Probe to extract and bring it to him. When the monsters defeated his probe, he almost sent another probe, but his computer told him that the "carbon-based lifeform" (Ginormica) was now too strong, and that the Quantonium could not be retrieved by a Robot. He came to Earth and sent a message to the citizens of Earth, then captured Ginormica, and in the process blasted Insectosaurus with a phasoid cannon. When Ginormica was on board the ship, she freed herself, Gallaxhar then fled into his Extraction Chamber where he would get the Quantonium out of Ginormica. He succeeded and cloned himself five times. This was enough for him to create an evil clone army of himself. After Dr. Cockroach destroyed his computer by stepping on the color buttons in the correct order while dancing, the self destruct system sounded. He attempted to escape, but once again was forced into combat with Ginormica. She then got her Quantonium back and escaped on Insectosaurus (who was now a butterfly). He tried to reverse the self-destruct but failed. It is apparent that Gallaxhar died in the explosion. He is voiced by Rainn Wilson.

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