The undersea nation of Seatopia sends the gigantic Megalon to destroy the world above - and it's up to Godzilla and a size-shifting robot, Jet Jaguar, to defeat him.
Godzilla vs. Megalon (Gojira tai Megaro) is a 1973 Japanese science fiction kaiju film featuring Godzilla, produced and distributed by Toho. The film is directed and co-written by Jun Fukuda with special effects by Teruyoshi Nakano and stars Katsuhiko Sasaki, Hiroyuki Kawase, Yutaka Hayashi, and Robert Dunham, with Shinji Takagi as Godzilla, Hideto Date as Megalon, Tsugutoshi Komada as Jet Jaguar, and Kenpachiro Satsuma as Gigan. It is the 13th film in the Godzilla franchise and Shōwa series.
The film was released in Japan on March 17, 1973 and theatrically in the United States in the summer of 1976 by Cinema Shares.