That was Einstein.

I don't think of him as a mad scientist, but I love him dearly.

(I think one of the jokes of the film must be that he's quite possibly the sanest person in it. For certain values of drunken back-alley plastic surgeon sane, I'm sure, but he's still the only character who seems to have noticed just how stupid this entire situation is: "Tell me, don't those plays you see all the time teach you anything?" He was my introduction to Peter Lorre.)