Champions that you can imagine in video games or other media
Ironicly my thoughts and yours have already been done or were used as inspiration for champion creation like Marth to
or Predator to 
Mario and Luigi
Gnar-rio
Lui-Yi.
Space Dandy
Because he is a Draven-dy guy in space.
Miltank
God help you if its Whitney's Miltank.
Zangief
Im still hoping we get a LoL fighting game.
Shenron and Goku
If LoL Japanese dub can get Goku's voice actor then these champs need dbz skins.
Splinter, Shredder and TMNT
Splinter,
Shredder,
Leonardo,
Casey Jones.
Every single wolf or werewolf in video games/anime/movies
Bayonetta
Vay-onetta.
Rocket Raccoon, Ratchet, Chua race from Wildstar
a furry who uses weapons, creates vehicles and weapons and loves using them... on you.
Tank Girl
She is just as nuts as TG in the comic.
The Mask
The Joker
Dampe' the Gravedigger
Pepsi Man
Firebrand (gargoyle's quest series)
Jehuty (zone of the enders)
Big Daddy or Bomberman
Bomberman 