The Mysterians is a 1957 Japanese epic science fiction film directed by Ishirō Honda, with special effects by Eiji Tsuburaya. Produced and distributed by Toho Co., Ltd., it is the first Honda-Tsuburaya collaboration filmed in both color and TohoScope, and stars Kenji Sahara, Yumi Shirakawa, Momoko Kōchi, Akihiko Hirata, Yoshio Tsuchiya, Susumu Fujita, and Takashi Shimura, with Haruo Nakajima and Katsumi Tezuka as Mogera. In the film, Earth's defense forces unite to combat an extraterrestrial race that desires to intermarry with human women and settle on the planet.
Inspired by the success of big-budget science fiction films in Japan and the United States, Toho executives became keen on producing a science fiction epic of their own. Producer Tomoyuki Tanaka recruited science fiction writer Jōjirō Okami to develop the story, which Shigeru Kayama later adapted for Takeshi Kimura's screenplay. Honda stated that three companies were involved in the film's production, which was the most in any tokusatsu production that he directed.
The Mysterians was released theatrically in Japan on December 28, 1957, as a double feature with Sazae's Youth.