Tralfamadore is the fictional home planet of aliens from several novels by the American author Kurt Vonnegut.

Details on the inhabitants of the planet vary from novel to novel. In Slaughterhouse-Five, they are beings who exist in all times simultaneously, and are thus privy to knowledge of future events, including the destruction of the universe at the hands of a Tralfamadorian test pilot. They kidnap Billy Pilgrim, the hero of the novel, and place him in a zoo on Tralfamadore with Montana Wildhack, an actress in pornographic films.

In The Sirens of Titan, Tralfamadore is the home of a civilization of machines, which dispatches Salo to a distant galaxy with a message for its inhabitants. After a part in his ship breaks, however, Salo is forced to land on Titan, a moon of Saturn, where he befriends Winston Niles Rumfoord. Rumfoord exists in much the same way as the Tralfamadorians of Slaughterhouse Five, while Salo appears to move in a linear fashion.

In God Bless You, Mr. Rosewater, Tralfamadore is a hypothetical foreign planet, used in a purely rhetorical sense as part of a thought exercise.