Ian, a likeable but severely solitary drifter, takes a job making repairs at the local church in the barren rural town of Canton Bluff. Eschewing human contact, Ian seems unnaturally leery of the impending full moon. Aware that Ian is a genuine werewolf, R.B. Harker (the owner of a traveling carnival) captures and forces the young man to work for his carnival, where he is put on display with other human oddities. To further complicate matters, Harker is revealed to have a monstrous secret of his own - he is a vampire.
Dick Bannister is the new field boss of the Ford Logging Company, a Canadian logging-crew during a time when conflicts with the powerful Consolidated Lumber Company, a bitter rival company, have turned bloody, like a private war. His boss, Miss Edith Ford, comes to inspect the lumberjack camp, bringing her doctor fiancé with her. Dick is attacked by his rivals and left for dead. His loss of blood is so great that he needs a transfusion, but no human will volunteer, so the surgeon uses a wolf as a source of the blood.
Wilfred Glendon (Henry Hull) is a wealthy and world-renowned English botanist who journeys to Tibet in search of the elusive mariphasa plant. While there, he is attacked and bitten by a creature later revealed to be a werewolf, although he succeeds in acquiring a specimen of the mariphasa. Once back home in London he is approached by a fellow botanist, Dr. Yogami (Warner Oland), who claims to have met him in Tibet while also seeking the mariphasa. Yogami warns Glendon that the bite of a werewolf would cause him to become a werewolf as well, adding that the mariphasa is a temporary antidote for the disease.
An Australian man named Ted, intricately connected to the previous three Howling films, arrives in a small western town where he begins to mingle with the local townsfolk, secretly recording his own enigmatic agendas into a tape recorder in his hotel room. At the same time a number of mysterious slayings appearing to be the work of a large animal begin to occur in the area. A detective investigates the case, helped by a priest who is certain the killings are the work of a werewolf, leading the two of them to uncover several clues that connect events from the majority of the latter part of the series.
The plot involves a scientist who has been discredited by his peers. He attempts to kill them off after he develops a secret formula that transforms his gardener into a murderous wolfman.
The Hammond family has been cursed since the Crusades, with family members dying or committing suicide under mysterious circumstances. When two people, including Oliver Hammond (John Howard) are attacked by an unknown creature, Robert Curtis (James Ellison) and his sidekick Christy (Heather Thatcher) are dispatched to investigate. Although the local townspeople are convinced that the attacks are the result of a curse upon the Hammond family, Curtis believes that he will be able to find a more scientific explanation for the attacks.
A Romany princess descended from Marie LaTour has the ability to change into a wolf at will, just like her late mother. When she learns that Marie LaTour's tomb has been discovered, she decides to use her talent to kill everyone who knows the location, because it is a sacred secret that only her people are allowed to know.
Wolves have been seen roaming around a girls' reformatory, and when the girls begin to get murdered, suspicion focuses on both the wolves and on a newly hired science teacher who might be a werewolf.
A psychic leads archaeologists into an Aztec pyramid where they discover two mummies, one of which turns out to be werewolf. Both mummies revive and stalk the scientists. The werewolf mummy is played by Lon Chaney, Jr. in footage from La Casa del Terror, his last film role as a werewolf.
Five men enter a train carriage in London bound for Bradley, and are joined by a sixth, the mysterious Doctor Schreck (Peter Cushing) whose name, he mentions, is German for "terror". During the journey, the doctor opens his pack of Tarot cards (which he calls his "House of Horrors") and proceeds to reveal the destinies of each of the travellers. This provides the framework to tell five horror stories.
A young attractive woman from a rich Mexican family is under a curse that causes her to transform into a wolf-woman at night and kill people. She falls in love with the doctor she sees (in order to get cured from her curse) who is also a werewolf. Unfortunately for both, their love filled killing spree comes to an end when they are killed by a trained, werewolf-killing dog.
Count Dracula (Alexander D'Arcy) and his vampire wife (Paula Raymond), hiding behind the pseudonyms of Count and Countess Townsend, lure girls to their castle in the Arizona desert to be drained of blood by their butler George (John Carradine), who then mixes real bloody marys for the couple. Then the real owners of the castle show up, along with Johnny, who is a serial killer or a werewolf depending on which version you watch. The owners refuse to sell, so Dracula wants to force them to sell. In a final confrontation, the vampires are forced to stand in the sunlight and dissolve.
Near the end of World War II, Satan saves Joseph Langdon/Philip Rogers (John Ashley) from death on condition that he become his disciple. Satan has Langdon inhabit the bodies of several people over the years, bringing out their latent evil. As it turns out, he becomes a hairy murderous beast — a werewolf on the rampage carrying out the evil deeds of the Devil for the next 25 years.
Paul Naschy returns as El Hombre Lobo for the sixth time as he searches for a cure to his lycanthropy by visiting the grandson of the infamous Dr. Jekyll. He is given a serum that transforms him into a Hyde-like personality in the hope that it will sublimate his werewolf self, but it results unfortunately in an even more savage monster. The film features a classic scene wherein the wolfman transforms in an elevator, much to the chagrin of a female fellow passenger. Famed Euro-horror star Jack Taylor played Dr. Henry Jekyll.
After Baron Henry von Frankenstein creates a bride his monster, he decides to make arrangements for a lavish wedding at the Transylvania Astoria Hotel. Many monsters are invited to the wedding including Count Dracula and his son, Ron Chanley the Werewolf, the Mummy, Dr. Jekyll and Mr. Hyde, the Invisible Man and his family, and the Creature from the Black Lagoon. Once the wedding guests arrive, they terrify guests and staff. Frankenstein's assistant Igor is jealous of the monster and wants the bride for his own. So Igor plots to steal her which doesn't go according to plan when the bride ends up snatched up by a Pterodactyl and lands in the clutches of a giant gorilla named Modzoola.