[Gemini-Phoenix]

There's still six weeks to go, and so many classic Batman characters not yet covered - Riddler, Harley Quinn, Mad Hatter, Killer Croc, Clayface, Poison Ivy, Mr Freeze, The Scarecrow, Ra's Al Ghul, Bane - There's still a chance that new exclusive SteelBooks will be announced in the coming weeks prior to release

As it stands at the moment, the Two-Face SteelBook appears to be the most common, available from several different retailers. The Catwoman SteelBook is perhaps second most common, with the Joker coming in third. At the moment of writing, the Penguin SteelBook happens to be the only true world exclusive, although that could change in the next few weeks...