Los Monstruos del Terror (translation: The Monsters of Terror), also known as Dracula vs. Frankenstein and Assignment: Terror, is a 1970 Spanish-West German-Italian horror and Sci-Fi film co-directed by Tulio Demicheli and Hugo Fregonese. (Fregonese quit midway through the production so the film was completed by Demicheli). Eberhard Meichsner was also credited as a director only in the British promotional material, but by all accounts he was not actually involved.

It is the third in a series of 12 films that Paul Naschy wrote and starred in featuring the werewolf Waldemar Daninsky, a role that was always played by Naschy. It stars Paul Naschy, Michael Rennie (his last film), Craig Hill and Karin Dor. Maria Perschy was supposed to play Maleva Kerstein, but Karin Dor wound up getting the part.

It was filmed in early Spring, 1969. The film was first released theatrically in Germany (as Dracula jagt [hunts] Frankenstein) on February 24, 1970, and in Spain (as The Monsters of Terror) on August 28, 1971. The film was also shown in France and in the U.K. as Dracula vs Frankenstein. In Belgium, it was shown as Dracula and the Wolf Man vs Frankenstein. In Mexico, it was released as Operation Terror, and in Denmark it was known as Frankenstein Og Blodsugerne/ Frankenstein vs The Bloodsucker. In the 1980s, the film was released on home video in France as Reincarnator. (Most of the film's variant titles did not even mention Naschy's Wolfman character.).

The film sold directly to late-night television in the U.S. in 1973, retitled Assignment Terror (since the title Dracula vs Frankenstein had already been used for the 1971 Al Adamson American film). In the U.K., the film played on a double bill with Peter Walker's 1970 horror film Die Screaming Marianne. Coincidentally, another Spanish film, released in 1972, also used the title Dracula vs Frankenstein.

Los Monstruos del Terror was originally going to be called El Hombre que Vino de Ummo (translation: The Man Who Came from Ummo), referring to Michael Rennie's space-man character, but the title was changed to The Monsters of Terror.

It was followed in the series by the 1970 film The Fury of the Wolfman.