See my influences for a basic idea but there is so much more to that, including this partial (alphabetical) list that will be added to as I remember more: Bad Brains, Black Sabbath, Death, Disturbed, Faith No More, Helmet, Korn, Metal Church, Metallica (up to And Justice For All), Midnight Syndicate, Monster Magnet, Pantera, Portishead, Radiohead, Scorpions, Sepultura, Snapcase, Soundgarden, System of a Down, Testament, Tool, Type O Negative, Warrior Soul and White Zombie.

The Saw films, Rob Zombie's films and so many more.

A Confederacy of Dunces by John Kennedy Toole, the Wheel of Time series by Robert Jordan and anything by horror master H.P. Lovecraft.