The Karnstein Trilogy is a series of vampire films produced by Hammer Films. They were notable at the time for their daring lesbian storylines. All three films were scripted by Tudor Gates. All three feature vampires of the noble Karnstein family, and their seat Castle Karnstein near the town of Karnstein in Styria, Austria.

A planned fourth film in the series, variously announced as either The Vampire Virgins or The Vampire Hunters, only got as far as the early draft stage.

The vampires of the Karnstein Trilogy differ from those of the Hammer Dracula films. Here, vampires can walk about in daylight and are immune to fire (their bodies are consumed, but their spirits just create or inhabit a new body). Their weaknesses are garlic and crosses, and the only ways to kill them is by staking them through their hearts or beheading them. Some of this lore is retained in the 1972 Hammer film Vampire Circus.