"The Day the Earth Stood Still" was released in 1951 and is considered a classic by modern-day standards and is noted for its intelligence and darkness. It tells the story of an alien and a giant robot who land on earth in their UFO immediately after World War II. They have come to deliver a message to the people of earth that they must live peacefully as their war-like behaviour is putting other planets in danger. The visitors have difficulty in communicating their message and thus must use other methods.
Based on a story by H.G. Wells and released in 1953, "War of the Worlds" is a story of invaders from Mars who have come to colonize Earth and wipe out its inhabitants. The story focuses less on the war and more on the human condition. Using high-end special effects, the film was considered ahead of its time both in story-telling and technology. The movie's source material was re-made by Steven Spielberg in 2005.
A good representation of the genre, "It Came from Outer Space" was released in 1953 and tells the story of an alien spacecraft that crashes in the Arizona desert. A local townsperson discovers the spacecraft and the alien; however his attempts of informing the townspeople fall short. Eventually the man begins to suspect that the alien may be having an effect on the townspeople. The movie combines science fiction with the psychological thriller.
Released in 1958 and directed by Ed Wood, "Plan 9 from Outer Space" is considered one of the worst films ever made and has received both infamy and a cult-following as a result. The movie tells the story of how aliens arrive on earth in order to turn deceased humans into vampires and zombies, with the ultimate aim of preventing humankind from developing a large bomb. The film is infamous for its low budget, poor production quality and bad acting.