Looks legit to me
If there's a comic book licensed game coming out, then it's a fairly safe bet that there will be some official tie-in action figures released too. NetherRealm's DC Comics-based fighter Injustic: Gods Among Us is no exception. Our friends over on Tomopop have posted an image of a fairly believable Joker figure.
The Joker figure here looks the part; the leather back of the jacket fits in with the meaner, more armoured vibe that Injustice seems to be going for. I'm sure we'll hear more news concerning a full line of figures before the game launches on April 16.