From Halopedia, the Halo wiki
Former Future President of the World.
The Dark Knight, Inception, Star Wars III, IV, V and VI, Red vs Blue, Star Trek, Sherlock Holmes, Hot Fuzz, Shaun of the Dead, Memento, and The Legend of the Hypocritical Washing Machine (I made that last one up).
Doctor Who, Torchwood, Firefly, House, Sherlock, Family Guy, The Simpsons, American Dad, Friends, Derren Brown specials, among others.
Frank Sinatra, Dean Martin, Sammy Davis Jr, Queen, Marty O' Donnell, "Weird Al" Yankovic, Murray Gold, Hans Zimmer, John Williams, Trocadero among others.
Halo novels, Harry Potter, A Series of Unfortunate Events, Nineteen Eighty-Four, Animal Farm, The Diamond Brothers, Alex Rider, To Kill a Mockingbird, among others.
Halo obviously, Half-Life, Portal, Fallout, Left 4 Dead, Mass Effect, Metal Gear Solid, Jak and Daxter, Ratchet and Clank, Star Wars: Bounty Hunter, Star Wars: Battlefront, Grand Theft Auto IV, and Pokémon main series.