The War of the Gargantuas is a 1966 Japanese Toho Studios 'Kaiju' science fiction horror film. It features Russ Tamblyn, Kumi Mizuno, Kenji Sahara, and Nobuo Nakamura.
An experimental lab animal called a gargantua escapes from his captors and is suspected to be the creature that is killing people all over the countryside. But when the gargantua from the lab appears at the same time as the evil gargantua, the two begin to battle across Japan.
Note: This print has not been completely dubbed into English.