Frankenstein Meets the Space Monster (1965) is a science fiction cult film, directed by Robert Gaffney and starring Marilyn Hanold, James Karen, and Lou Cutell. The film was released in Great Britain 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.