This is a little project I've been considering for awhile--reviewing every single serious adaptation of Joseph Sheridan LeFanu's Carmilla, or at least the ones recorded. For the record, I will only review stage productions I've actually seen--which at present is zero but hopefully that will change.
In 1970 Hammer Studios looked back at a solid decade of success, remembered today with fondness by fans of genre film. They had more-or-less discovered Peter Cushing and Sir Christopher Lee (among others). Whereas Universal Studios' horror classics had been icons for generations, Hammer re-invented those same ideas with a distinctly British and more modern slant. Arguably their greatest success in this direction was Dracula. Lee at last supplanted Lugosi in many imaginations as the ultimate Dracula. Other vampire films followed, bringing fangs and bare bosoms as well as technicolor blood to the screen.
The Vampire Lovers marked a new mini-franchise for Hammer. Instead of linking the story (however slightly) to Bram Stoker's famous novel, instead they went after LeFanu's atmospheric tale of tortured love . Of course the lesbianism of the tale got maximum attention (or at least as much as they thought possible under the eyes of the censors), along with pleasantly copious amounts of partial nudity by lovelies such as Ingrid Pitt and Madaline Smith. No complaints there! But they also did what one expects in a Hammer film...
Extra blood, extra violence, extra sex. For example, this film has Carmilla physically seduce the heroine (re-named Emma for some reason) then do the same to her governess Madame Perradon (Kate O'Mara, later to achieve genre fame as The Rani on Doctor Who)! Far more was made of people suspecting a vampire might be in their midst, and Carmilla's response was to seduce/slaughter those who stood in her way. Along those lines, much more was made of the final "hunting" of her grave, intercutting those scenes with Emma's rescue by a suitably young male love interest (something totally absent in the original).
Unlike almost any other version, this lurid (for its time) titillation feature captured an essence missing from virtually all other versions. Carmilla in this film is a tragic figure, one literally in tears as she is forced to feed, and broken-hearted at seeing Emma's reaction to the truth. Pitt is actually a bit old for the part, but she does a wonderful job of coming across as a someone in love rather than lust. Nor is that a function of the performance alone. We see the vampire prey upon another young woman (this one named Laura) without as much drama. Carmilla is so taken with Emma she tries to take her away, precisely where and to what end is not clear. Likewise Carmilla seems influenced/dominated by a strange man in black (a role initially offered Christopher Lee but he turned it down). Sexism? Perhaps. But the goal here pretty clearly remained to lend sympathy to the "monster" by making her not completely responsible for her actions. Likewise, before her beheading by Cushing's General Spielsdorf, Pitt's character seems almost to welcome it.
Hammer went on to make two other films more-or-less sequels or prequels to this one--Lust for a Vampire and then Twins of Evil. Pitt refused to reprise her role either time. Under pressure from censors, each film had less and less lesbian content. The supposed "love story" of the former was at least some attempt at capturing the chemistry Pitt and Smith clearly found. Alas, it didn't work. One other movie, Captain Kronos Vampire Hunter, had some tiny connection to the "Karnstein Trilogy" but nothing more.
So we are left with what should have been the trashiest version, but which in some ways was the most faithful.