Weeks ago, Ed Boon promised the announcement of four new playable characters for Mortal Kombat vs. DC Universe, two from each side, at the annual Comic-Con event. Those four characters have indeed been revealed, but only one currently possesses his own render. IGN was given this image as an exclusive earlier today:

The clown prince of crime from Batman's universe can be safely added to the list of confirmed characters! The Joker sports his traditional attire and appears to be standing in front of the Gotham City Police Department, plotting some sort of fiendish crime no doubt.

If a higher res image becomes available from the official site, this thread will be updated with it. Until then, thanks to IGN and for the lead on this!