Gigantis, the Fire Monster

Hiroshi Koizumi

Shoichi Tsukioka

Keye Luke

Shoichi Tsukioka (voice)

Setsuko Wakayama

Hidemi Yamaji

Aya Oyama

Hidemi Yamaji (voice)

Minoru Chiaki

Kôji Kobayashi

Marvin Miller

Koji Kobayashi / Narrator (voices)

Masao Shimizu

Dr. Tadokoro

Mayuri Mokushô

Yasuko Inouye, Koji's girl

Takeo Oikawa

Osaka Chief of Police

Minosuke Yamada

Chief of Civil Defense

Takashi Shimura

Doctor Yamane

Sonosuke Sawamura

Foreman Shibeki

Yoshio Tsuchiya

Member of Osaka's SDF Tajima

Yukio Kasama

President of Fishery Koehi Yamaji

Paul Frees

Doctor Kyohei Yamane, Commander of Osaka's SDF Terasawa, President of Fishery Koehi Yamaji (voices)

Ren Yamamoto

Commander of Landing Craft Ikeda

George Takei

Commander of Landing Craft Ikeda (voice)

Seijirô Onda

Commander of Osaka's SDF Terasawa

Shin Ōtomo

Convict Leader

Senkichi Ōmura

Convict

Haruo Nakajima

Gigantis

Katsumi Tezuka

Angurus

Shōichi Hirose

Convict