The phrase "no longer exists before" gets meaningful when it comes to horror movies. The three best on this list, compiled by The Guardian, are before the 1980s. Have fun, or in this case, be horrified.
3. The Exorcist (William Friedkin, 1973)
A teenage girl is captured by a mysterious spirit and her mother asks for the help of two priests to save her. The movie hits you with a handful of fear and slaughtered with horror. The effects used are impressive to this day and the confrontation between good and bad, feverish.
2. Rosemary's Baby (Roman Polanski, 1968)
A young couple flatters into an apartment and are surrounded by neighbors and strange happenings. When the woman suddenly gets pregnant, the fear of the unborn baby's safety invades her life. Based on Ira Levin's book, Mia Farrow's performance is unforgettable.
1. Do not Look Now (Nicolas Roeg, 1973)
A married couple mourns the death of their little girl in Venice. There they meet with two sisters, one of which has predictive power and gives a warning from the other world. The performances are wonderful, signs of existence beyond the tomb to frighten, and meditation on the time, memory and feeling of marriage strike where it is not expected.