Director: Jun Fukuda
Inventor Goro Ibuki creates a humanoid robot named Jet Jaguar. It is soon seized by an undersea race of people called the Seatopians. Using Jet Jaguar as a guide, the Seatopians send Megalon as vengeance for the nuclear tests that have devastated their society.
Katsuhiko Sasaki
Inventor Goro Ibuki
Yutaka Hayashi
Hiroshi Jinkawa
Hiroyuki Kawase
Rokuro 'Roku-chan' Ibuki
Kanta Mori
Japan Special Defense Forces Chief
Kotaro Tomita
Lead Seatopian Agent
Ulf Otsuki
Seatopian Agent
Sakyo Mikami
Truck Driver's Assistant
Fumiyo Ikeda
Man from Unit 1
Robert Dunham
Emperor Antonio of Seatopia
Gentaro Nakajima
Truck Driver
Ralph Jesser
Antonio's Aide (Radio Operator in White)
Shinji Takagi
Godzilla
Hideto Odachi
Megalon
Tsugutoshi Komada
Jet Jaguar
Masachika Mori
Jet Jaguar
Kenpachirō Satsuma
Gigan
Gorō Naya
Emperor Atonio of Seatopia (voice)
Eisuke Nakanishi
Narrator
Haruo Nakajima
Godzilla (archive footage) (uncredited)
Kôetsu Ômiya
Anguirus
