120 Days of Sodom
Made in 1975, 120 Days of Sodom or Saló as it was also referred, was made to purely disgust the viewer. This movie is hard to watch in 2019, let alone in the 70s.
Cannibal Holocaust
This movie masqueraded as a found footage film, and they did such a good job of making this look like such that the director got arrested on obscenity charges and then arrested for murder. Real talk.