Didn't recognize him in Boardwalk Empire

I watched BE when it first aired and A Serious Man shortly after release. I never put two and two together. I watched Steve Jobs the other night and was like "Hey, it's Larry Gopnik" because he plays a similar, submissive nerd.

But it took me visiting his page to ask myself who he was in BE, and then it clicked. His performance as Arnold Rothstein is so creepy and almost otherworldly, or as Gyp Rosetti put it, creeping around like a *beep* dentist with ether. I would have never recognized him. He has the same voice but the delivery of his lines and his mannerisms are so different, I still wouldn't have recognized him if I didn't look it up.