Black Mask

From the Lego Batman Wiki

Black Mask is one of Batman's enemies.He also is one of Red Hood's enemies. He can be unlocked in the DS Villain Hunt. To unlock the custom character pieces to make him you must find all 300 minikits on the console versions. After that you can buy him for 50,000 studs. Black Mask can be created in the create a Hero/Villian a video can be shown on youtube.

On the DS version you can unlock him when you find him on Villian Hunt then you can buy him for 600,000 studs.