ClarkesWorld, the Hugo Award-winning SF/F magazine, has a great essay on the history of Hammer Films summarizing how 1955's The Quartermass Experiment and Hammer's subsequent SF films influenced the genre.
Hammer Horror is well-known for it many Frankenstein, Dracula, Mummy and "Cave Girl" films (see Nerd-Feather's microreview of The Satanic Rites of Dracula), as well as a number of other monster movies and psychological thrillers from the 50s, 60s and 70s. Hammer has had a pretty successful comeback in recent years: Let Me In (the American remake of Let the Right One In) and The Woman in Black (Daniel Radcliffe's first post-Harry Potter film) are both from Hammer.