Some of the scariest films I have seen could be a close race between Umberto Lenzi's Eaten Alive and Cannibal Ferrox, Lucio Fulci's The Beyond, Mario Bava's Kill Baby Kill! and Shock, Dario Argento's Phenomena, Tenebre, Deep Red, and Stendhal Syndrome, Tales From The Crypt(1972), Night Train Murders, to name a few that I can think of right offhand...