Dr. Jekyll And Mr. Hyde (1931)

Starring Fredric March, Miriam Hopkins, Rose Hobart, Holmes Herbert, Halliwell Hobbes
Directed by Rouben Mamoulian
(actor & director credits courtesy IMDB.com)

The brilliant young Dr. Jekyll risks his impending marriage and standing in society in experiments to unleash his own dark half, a hideous alter ego who is as depraved as Jekyll is good and decent.

For my money we have here the best adaptation ever of Robert Louis Stevenson's famous novel, and there have been quite a few, but March's exceptional performance and the excellent photography of Karl Struss make this one rise to the top.  Many actors have played Jekyll and Hyde, and many brilliantly so, but March is so unrecognizable as Hyde, another actor could have been credited with Hyde's performance, and I think all would have believed it.  It's true that March's features are hidden under the ape-like Hyde's makeup and toothy grin, but his voice, his mannerisms, and his obsessive stare are so different from what we've seen from March as Jekyll or in his other films, it's no wonder he won the Oscar that year (tied with Wallace Beery).  Struss' camerawork adds excitement to the film, opening with a long sequence where we see through Jekyll's eyes alone, in counterpoint to the coming emphasis on how characters see him and his alter ego, and the visual trickery Struss and editor William Shea employ during the Hyde transformation sequences make them seem vibrantly real.  The picture also has excellent art direction, a talented supporting cast, and Hopkins' pre-Code attempted seduction of Jekyll in the film's early moments still packs plenty of heat.