First Men In The Moon is a 1964 science fiction film directed by Nathan Juran . The film is an adaptation of the H.G. Wells novel The First Men in the Moon and is also known as H.G. Wells' First Men in the Moon. (The title of the novel includes the word the twice; the film titles only once). The novel was adapted for the screen by the noted science-fiction scriptwriter Nigel Kneale.

Ray Harryhausen provides stop-motion effects, animated Selenites, giant caterpillar-like "Moon Cows", and a big-brained Grand Lunar.

Joseph Cavor is played by Lionel Jeffries, Katherine 'Kate' Callender by Martha Hyer, and Arnold Bedford by Edward Judd .

The movie begins in the 1960s with agroup of American astronauts, believing themselves to be the first lunar explorers, discovering a Union Jack on the moon's surface and a note naming Bedford and Cavor. The American authorities trace the aged Bedford to a British nursing home, and he tells them the story of the true first lunar expedition.

In 1899, Victorian Britain, Professor Joseph Cavor invents Cavorite, a substance that will allows objects to deflect the force of gravity. He builds a spherical spaceship that travels to the Moon using the antigravity properties of Cavorite. He and his companions travel to the lunar surface where they are captured by the insect-like Moon inhabitants, the Selenites, which live in huge cities beneath the Moon's surface.

The Selenites quickly learn English and interrogate Cavor, who believes they wish to exchange scientific knowledge. The more practical Bedford eventually manages to persuade Cavor that the Selenites are interested in conquering the Earth using Cavorite. Cavor helps Bedford and Callender to escape but is left behind on the Moon.

Returning to the present, the American astronauts break into the Selenite city, only to find it deserted and decaying. In a plot twist "borrowed" from Wells' other famous novel The War of the Worlds, Bedford realises that the Selenites must have been killed off by Cavor's common cold viruses to which they had no immunity.