Frankenstein Meets the Space Monster (sometimes stylized as Frankenstein Meets the Spacemonster) (1965) is a science fiction cult film, directed by Robert Gaffney and starring Marilyn Hanold, James Karen and Lou Cutell. It was filmed in Florida and Puerto Rico in 1964.

The film was released in the United Kingdom as Duel of the Space Monsters. It is also known as Frankenstein Meets the Space Men, Mars Attacks Puerto Rico, Mars Invades Puerto Rico and Operation San Juan. Released by the Futurama Entertainment Corp., it was released on DVD by Dark Sky Films in 2006. In the United States, it was initially released on a double feature with Curse of the Voodoo.

The film tells the story of a facially-damaged android robot who fights alien invaders. Despite the title, neither Dr. Frankenstein nor Frankenstein’s monster appear in the film. However, it is stated near the beginning of the movie that the android is partially built from human pieces and he is also often called by the first name of Frank.