Hellraiser is a series of horror films exploring the themes of sadomasochism and morals under duress. The first film is based on the critically acclaimed novella The Hellbound Heart by Clive Barker, who also wrote the screenplay and directed the first film. As of 2006, there have been seven sequels.(from wikipedia).
Phantasm first released in 1979 spawned 3 sequels with another Phantasm V due out in 2008.