Godzilla vs. Gigan (Japanese: 地球攻撃命令 ゴジラ対ガイガン, Hepburn: Chikyū Kōgeki Meirei Gojira Tai Gaigan, lit. Earth Destruction Directive: Godzilla vs. Gigan), is a 1972 Japanese kaiju film directed by Jun Fukuda, written by Shinichi Sekizawa, and produced by Tomoyuki Tanaka, with special effects by Teruyoshi Nakano. Distributed by Toho and produced under their effects-based subsidiary Toho-Eizo, it is the 12th film in the Godzilla franchise, and features the fictional monster characters Godzilla, Gigan, Anguirus, and King Ghidorah. The film stars Hiroshi Ishikawa, Yuriko Hishimi, Tomoko Umeda, and Minoru Takashima, alongside Haruo Nakajima as Godzilla, Kenpachiro Satsuma as Gigan, Koetsu Omiya as Anguirus, and Kanta Ina as Ghidorah. It is the last film in which Godzilla was portrayed by Nakajima after playing the character since the original 1954 film; he subsequently retired from suit acting.

Godzilla vs. Gigan was released theatrically in Japan on March 12, 1972. It received a wide theatrical release in the United States in 1977 by Cinema Shares under the title Godzilla on Monster Island and was released in the UK by Miracle Films the same year as War of the Monsters.

The film was followed by the 13th film in the Godzilla franchise, Godzilla vs. Megalon, released on March 17, 1973.