To unlock these characters you must first grab the Golden Ticket from Bogomart. Which is directly after the starting area of the game.

Character	How to Unlock
Bat(Charlie)	Complete the Movie Theater dungeon on Total Anarchy.
Blood Mage(Charlie)	Complete the Movie Theater dungeon on Chaos.
Corpse(Rex)	Complete the Movie Theater dungeon on Total Anarchy.
Enchantress(Kelly)	Complete the Movie Theater dungeon on Normal.
Frostwraith(Charlie)	Complete the Movie Theater dungeon on Normal.
Half Yeti(Rex)	Complete the Movie Theater dungeon on Normal.
Icemonk(Tommy)	Complete the Movie Theater dungeon on Normal.
Lich(Lester)	Complete the Movie Theater dungeon on Normal.
Necromancer(Rex)	Complete the Movie Theater dungeon on Chaos.
Paladin(Tommy)	Complete the Movie Theater dungeon on Chaos.
Scarecrow(Lester)	Complete the Movie Theater dungeon on Total Anarchy.
Siren(Kelly	Complete the Movie Theater dungeon on Chaos.
Skeleton(Tommy)	Complete the Movie Theater dungeon on Total Anarchy.
Warlock(Lester)	Complete the Movie Theater dungeon on Chaos.
White Wolf(Kelly)	Complete the Movie Theater dungeon on Total Anarchy.