"Forbidden Planet" (1956): Arguably the quintessential science-fiction film, starring Leslie Nielsen as a spacecraft commander who lands on the planet Altair IV and discovers Robby the Robot, an alluring Anne Francis and a strange monster roaming the barren landscape. Wildly imaginative, with nods to Shakespeare, Freud and Jung; also singularly creepy, thanks partly to the groundbreaking electronic score by Louis and Bebe Barron.
'2001: A Space Odyssey'
"2001: A Space Odyssey" (1968): Stanley Kubrick's epic remains the gold standard of modern sci-fi even after all these years. The malevolent computer HAL, the striking classical score and Douglas Trumbull's hypnotic light-show -- in which space travel becomes a metaphysical, even mystical experience -- have all been repurposed in "Interstellar," and probably will be for decades to come.
"Barbarella" (1968): Times have changed since Roger Vadim cast his wife, Jane Fonda, as a wide-eyed, big-bosomed innocent who travels through space submitting to the sexual needs of intergalactic males. Featuring cringe-worthy innuendo and a philosophy best described as priapic, "Barbarella" is one of those astounding camp films that almost defies belief. It's also famous for giving the pop band Duran Duran the idea for its name.
'Planet of the Apes'
"Planet of the Apes" (1968): Before motion-capture and CGI, latex masks and fake fur were enough to convince audiences that apes could conquer humans. Even today, the movie holds up, thanks in no small part to some indelible peformances: Charlton Heston as human astronaut George Taylor, and Kim Hunter and Roddy McDowall as the intelligent chimpanzees Zira and Cornelius. The movie has been remade and rebooted, but never quite equaled.
"Alien" (1979): Ridley Scott's attempt to cash in on the "Star Wars" craze resulted in one of cinema's greatest crowd-pleasers, a mix of science-fiction, monster movie and slasher flick. Sigourney Weaver turns what could have been the scream-queen role of Ripley into a tough-as-nails survivor; the alien itself, designed by H.R. Geiger, is still being copied by effects designers today.
"Moonraker" (1979): In the wake of "Star Wars," it was only a matter of time before James Bond ventured into space. The whole project could have been a groaner, but Roger Moore was hitting his campy, swingin' stride as 007, and he squared off against one of his best villains in Richard Keil as the metal-mouthed Jaws. The big budget went toward lavish, eye-popping visuals and resulted in an Oscar nomination for effects. Racking up $210 million worldwide, "Moonraker" became the Bond series' highest-grossing entry at the time.
"Gravity" (2013): Sandra Bullock and George Clooney play a couple of astronauts whose space-station is shattered by an asteroid storm. Though the story may feel slim, the film was heralded as a technical masterpiece for its physics-defying visuals (whirling space structures, teardrops that float off faces) and dazzling cinematography. "Gravity" became a critical and commercial hit, racking up 10 Oscar nominations and winning seven, the most of any film that year.