What a criminally underrated actor! Atwill, like Price (who himself would later go on to reprise Atwill's performance in Mstery of the Wax Museum) , specialized in an urbane brand of villainy. Suave and sophisticated, Atwill could also very easily project psychopathic malevolence with nothing more than a passing glance.
I would also highly recommend the book, "Hollywood's Maddest Doctors: Lionel Atwill, Colin Clive, George Zucco," as well as what I think are his three finest cinematic performances,
Murders In The Zoo
Son of Frankenstein
Man Made Monster