For the episode, see MST3K 103 - The Mad Monster.

The Mad Monster is an American horror film produced and distributed by Producers Releasing Corporation.


Dr. Lorenzo Cameron injects a serum made from a wolf's blood into his cooperative servant Petro, who loses consciousness, grows fur and fangs, and awakens as a wolfman. Cameron imagines his former colleagues who ridiculed his theory that transfusions of wolf blood could be used to give a human being wolf-like traits. He recalls how the scientific community, the press, and the public all ridiculed him, which cost him his position at the university.

With the proof of his theory's accuracy, Cameron now plans to have his wolfman kill his former colleagues. He then administers an antidote to Petro that transforms him back into a human. Petro remembers nothing.

The following night, Cameron turns Petro into a wolf and sends him to the swamp. Petro enters a nearby home and killed a little girl. Cameron then sets up elaborate scenarios in which Petro is alone with each scientist when he becomes a wolf. The more times Cameron does this, the more Petro's transformations into a wolfman become unpredictable.

Cameron's daughter Lenora is romantically involved with Tom Gregory, a newspaper reporter who is investigating the death of the little girl. As the professors are killed off one by one, Gregory begins to suspect that Cameron is behind the slayings.

The principals are in the Cameron home when a thunderstorm begins and a bolt of lightning sets Cameron's laboratory on fire. Lenora and Tom escape from the house after encountering Petro in wolf form. Petro turns on Cameron and kills him, just before the fire brings the house down on both of them.


  • George Zucco as Dr. Lorenzo Cameron
  • Glenn Strange as Petro
  • Anne Nagel as Lenora Cameron
  • Johnny Downs as Tom Gregory
  • Gordon De Main as Professor Fitzgerald
  • Reginald Barlow as Professor Warwick
  • Robert Strange as Professor Blaine
  • John Elliott as Professor Hatfield
  • Sarah Padden as Grandmother
  • Ed Cassidy as Father
  • Mae Busch as Susan
  • Henry Hall as Country Doctor
  • Slim Whitaker as Policeman
  • Gil Patric as Lieutenant Detective


  • The Mad Monster was released shortly after The Wolf Man (1941) but cost a fraction of Universal's more elaborate lycanthropic exercise.
  • Glenn Strange, who plays Petro the werewolf, would later take up the role of Frankenstein's Monster in several of Universal's features.
  • Anne Nagel's character name in this film is possibly a nod to her having portrayed Lenore "Casey" Case in the two Green Hornet serials produced by Universal Studios.
  • Filmed in five days.

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