Doctor Gogol from Mad Love. Have you seen that one yet? Only Peter Lorre can get away with frequenting a snuff theater (Grand Guignol with the numbers filed off), stalking the heroine, attending beheadings for the fun of it, and gaslighting his mentally unstable patients, and STILL be lovable and pitiable and the woobie of the story.

Runner-up, Dr. Rotwang, but you know about me and him already.

I love Peter Cushing!Dr. Frankenstein, but the other two got to me first.