Ooh this is a really good topic!
Heh, most of the ones I've seen have been mentioned already. xD Hm.. oh! Fox and the Hound, Pirates of the Caribbean, Super Smash Bros. (though the characters are from their own games, but thought I add that in anyways), Gravity Falls, Okami, Inuyasha, Courage the Cowardly Dog, Regular Show, Spyro, Crash Bandicoot and Sly Cooper. That's most of what I can think of that I experienced about fandoms in FeralHeart.