19. Sister Gertrude - Killer Nun (1978)
Of course I had to get a little bit of exploitation into the list (in this case nunsploitation) but Anita Ekberg's portrayal of Sister Gertrude the demented psycho nun is so entertaining I put it on the list. I think she used to be just a regular nun until she had to have brain surgery. This drove her insane and she was forced back to her job as a nurse by the Mother Superior. Among Gertie's psycho bad behaviour, we find her in full make up at all times (because that's what the Vatican decrees for nuns, starting a lesbian relationship with a fellow nun, picking up random men for sex, taking over the hospital (which is for geriatrics) and instituting a reign of tyranny - stomping on an oldie's false gnashers and forcing the poor old dears into rigorous calisthenics. The whole thing is so brilliant, I have never yet seen a psycho nun portrayal that bests Sister Gertrude. She is a wonderful psycho and the fact that she is a nun makes the movie all the more salacious. One for lovers of camp Italian cinematic psycho hijinks.