Doctor Who, Breaking Bad, Game of Thrones, Firefly, Rayman, Buffy the Vampire Slayer, Marvel Cinematic universe, Veronica Mars, Sherlock, House of Cards, Dollhouse, True Detective, Adventure Time, Robot Chicken, Bravest Warriors, How I Met Your Mother, Avatar the Last Airbender, Futurama, South Park
It's shame that you can't discuss about your headcanons and theorise about fanfics in Storyline and Theories forum, but you can discuss about Expanded Multiverse which is just a giant fanfic itsefl... Seems fair.