Well, that has got to be one of the creepiest header images ever. I don't even have coulrophobia and I'm creeped the eff out right now.
The man in the harlequin costume you see above is GameStop's pre-order bonus for Assassin's Creed: Brotherhood. He's scary and will most likely become readily available for the general public only a few weeks after the game drops as store-exclusive pre-order bonuses usually do.
There aren't many details on what skills the Harlequin will have other than an ominous description from the GameStop page that says "You call yourself the Harlequin. Your victims will call you a walking nightmare." Judging from that shot I'm hoping one of his signature kills is jumping out from behind a corner and shouting "BOO!"