When a meteor lands from Outer Space, it is found by an old man who pokes at the meteor with stick. The meteor opens up to reveal a gelatinous monster that attaches itself to the old mans arm. He is found by two teens, Steve Andrews (McQueen) and Jane Martin (Steve Corsaut) and Jane Martin (Aneta Corsaut), and take him to the local Doctor where the monster continues to dissolves the old man but also eats the Doctor and his nurse as well.

Steve and Jane witness the doctor's death and try to inform the local police but they don't take the teens seriously. The Blob continues to stalk the small town despite the warnings. Steve and Jane must try to convince the town of monster before it's too late.

Directed by Irvin Yeaworth and released by Paramount Pictures.

In 1972 a sequel was released entitled Beware! The Blob and the film was remade in 1988. The also has been referenced and made cameos in many movies as well.

The town of Phoenixville, Pennsylvania (where the film was filmed) a yearly festival, called Blobfest. The film is shown in the original theater in the film with a yearly recreation of the audience run out scene. The Diner also is still open for both regular business and tourist.