Unique Dungeon Heroes

Hey, look. A thread not about technical issues.

Is there any list for heroes which unique apperances in this game? I'm mostly interested in Dungeon heroes but all factions can apply.
I know of the heroes that you gain from platinum rank as well as the ones from completing the campaigns.

But for Dungeon so far I really only know of one playable hero with unique apperance. And he does not exactly look very interesting.