She was regarded by many fans as the queen of Hammer Horror films.
The star's death comes weeks after film-maker Roy Ward Baker, who directed Pitt in The Vampire Lovers, died at the age of 93.
Pitt's daughter told the BBC News website that her mother's death had come as a "huge surprise".
After the actress has collapsed recently, doctors told her was she suffering from heart failure.
"She could be incredibly generous, loving, and she'll be sorely missed," Mrs Blake said.
She added that she wanted her mother to be remembered as the Countess Dracula with the "wonderful teeth and the wonderful bosom"
Official Hammer historian Marcus Hearn paid tribute to the star, calling her a "talented actress and fine writer".
A good friend of the actress, Mr Hearn said she was "gloriously uninhibited" and "great fun to be with".
"All fans of Hammer and of British horror are going to miss her terribly”Marcus Hearn Official Hammer historian. He added: "She was partly responsible for ushering in a bold and brazen era of sexually explicitly horror films in the 1970s, but that should not denigrate her abilities as an actress."
Although she was not the first female star of a Hammer film, Mr Hearn said she had always been "very proud" of becoming the first prominent female protagonist in a Hammer after her role in The Vampire Lovers.
"All fans of Hammer and of British horror are going to miss her terribly," he said.