Gigan returned in Godzilla vs. Megalon, as he was called by the Seatopians to help them conquer Earth. He arrived to help Megalon battle Godzilla, and they nearly killed him. Jet Jaguar attacked Gigan, but he was also defeated. The two monsters regained their strength, and they fought Gigan and Megalon off again. Gigan retreated back to space, and Megalon returned to Seatopia.