The 1970s were a great decade for horror. The "new permissiveness" allowed filmmakers to push the envelope on subject matter, as well as nudity and, of course, gore. Lots and lots of gore.
Making a top ten list is often arbitrary, and this one is no exception, especially considering how many horror flicks were made in the '70s, a very busy decade for horror. At the time, there were still plenty of drive-ins and grindhouses needing a steady supply of the gothic, the ghostly, and the gory, and filmmakers like John Carpenter, Brian DePalma, George Romero (whose "Dawn of the Dead" is covered on another list, "The Greatest Zombie Movies Ever Made"), and Dario Argento producing masterworks of the genre.