Gorgo is a 1961 British Giant monster movie that is generally accepted as an honorary kaiju movie. Directed by Eugène Lourié, it tells the story of an underwater monster's capture off the coast of Ireland. The monster is taken to London to be featured as a circus attraction. The film borrows elements from other monster movies, such as Godzilla and King Kong.
As the film commences, Captain Joe Ryan is salvaging for treasure off the coast of Ireland, when a volcano erupts, nearly sinking his ship. Ryan and his first officer, Sam Slade, take the ship to Nara Island for repairs. As they enter harbour, they discover the floating carcasses of marine animals, the first hint that something dangerous was awoken by the volcano eruption.
Ryan and Slade consult McCartin the harbour master, who also has archeological pretensions: he has been salvaging in the harbor. Some of his men have disappeared mysteriously; it turns out that one has died of fear. After dark, a monstrous creature surfaces, attacks a group of fishermen, then comes ashore to wreak havoc on the island. This dinosaur-like creature is supposedly 65 feet tall. The people of the island finally drive it off.
Ryan and his crew manage to capture the monster and haul it aboard their ship, tying it to the deck. Soon, university scientists arrive on Nara, hoping to collect the monster for study, but Ryan has been offered a better deal by Dorkin the owner of a circus in London. When the ship arrives in London, the circus owner names it "Gorgo", after a name in Classical mythology. It is exhibited to the public in Battersea Park.
The scientists examine Gorgo, and conclude that he is not yet an adult, and that his mother must be nearly 200 feet tall. On that note of foreboding, we cut to Nara Island as Gorgo's mother ("Ogra") attacks. Ogra trashes the island, sinks a Royal, and resists attack from other warships. Later, Ogra comes ashore in London, still looking for her son, goes on a rampage and , despite being bombarded by tanks and infantry it continues. Jets attack Ogra, but with no effect. Having demolished much of London, Ogra rescues Gorgo, and both mother and son return to the sea.