'Frankenstein vs. Subterranean Monster Baragon') is a 1965 kaiju film directed by Ishirō Honda, with special effects by Eiji Tsuburaya.

The film stars Nick Adams, Kumi Mizuno and Tadao Takashima, with Koji Furuhata as Frankenstein and Haruo Nakajima as Baragon.

[7][8] In the film, scientists investigate the origins of a mysterious boy and his resistance to radiation that makes him grow to monstrous size, while a second monster ravages the countryside.

Meanwhile, Bowen and his team find out that the strange boy is growing in size due to an intake of protein.

Afraid of his strength, the scientists lock and chain the boy in a cage and Sueko, who cares for him, feeds him some protein-filled food to sustain him.

Ignoring Bowen's suggestion to think it over, Kawaji tenaciously attempts to sever one of the limbs of the boy-turned-giant, now called "Frankenstein".

A severed, still-living hand of Frankenstein's is found, proving Riesendorf's theory, though it dies shortly after accidentally trapping itself under a grate without a supply of protein to sustain it.

To Bowen and Sueko's shock, Kawaji reveals his plans to kill Frankenstein by blinding him with grenades in order to recover his heart and his brain.

Kawaji states that the immortal heart will live on and they may one day see him again, but Bowen believes that Frankenstein is better off dead.

With a completed script by George Worthing Yates (retitled as King Kong vs. Prometheus, in reference to the original Mary Shelley book), Beck generated some interest in Hollywood but failed to secure funding and reached out overseas.

O'Brien attempted to sue (presumably Beck) over the deal with Toho but dropped the lawsuit due to mounting attorney fees and died on November 8, 1962.

Sekizawa failed to finish the story treatment, citing lack of inspiration, and abandoned the idea.

The deal also allowed Saperstein to attach Hollywood actors as the leads, to provide half the financing for territorial rights, and consultation on the scripts.

[13] The idea for Frankenstein vs. Godzilla originated from UPA, with Jerry Sohl and Reuben Bercovitch providing the initial concept.

Afraid the giant would start eating people, Godzilla would be awakened from slumber in the Kurile Trench by the JSDF and goaded into a fight with the monster in hopes of destroying him.

[15] Honda criticized the decision by Toho and UPA to include a kaiju, calling it "convenient", and originally wanted to explore the tragedy and immoral science behind Frankenstein instead.

Furuhata wore green contact lenses to emulate a Caucasian look, a flat-head prosthetic and brow resembling Jack Pierce's Frankenstein Monster design and large shirts and loincloths.

Honda had originally wanted to explore more of the science-gone-wrong theme, but was forced to change the story in the middle to reach a climactic monster battle.

[4] The film was released theatrically in the United States as Frankenstein Conquers the World on July 8, 1966 by American International Pictures.

The international version (titled Frankenstein vs. the Giant Devilfish) features an audio commentary by Sadamasa Arikawa, the film's special effects photographer.