d. Edward Dmytryk (1943)
Noted endocrinologist John Carradine has made the familiar transition from dedicated scientist to unhinged maniac. He steals a friendly gorilla from a circus and implants it with the glands of his nurse, who made the mistake of suggesting that he was probably working too hard. The result, somewhat improbably, is a beautiful, exotic looking woman who he names Paula Dupree (she's played by Acquanetta, 'the Venezualan Volcano', actually born in Wyoming).
Because he's mad and drunk on his own cleverness, the doctor takes his creation back to the circus, where it becomes clear that Paula has a miraculous power over animals: they are shit scared of her. She is immediately enlisted as an assistant to the big cat tamer, her main role being to stand outside the cage in a spangly outfit just looking intently at the lions and tigers*. Occasionally, if they become unruly, she will look harder, perhaps arching an eyebrow. It's nice work if you can get it, though, presumably, there isn't a massive amount of demand for that sort of talent.
Falling in love with the big cat tamer sends powerful emotions coursing through her reconfigured body, however, breaking her new glands and unleashing her inner gorilla. By the time she is shot by an over zealous cop (nothing much changes in America) she has fully reverted to her old, hairy animal self, but there is a moment roughly halfway between her initial retro-transformation from human lady to ape woman to gorilla in which she is probably the most beautiful thing I have ever seen.
* These scenes feature Clyde Beatty, the world famous animal trainer. It is amazing to watch him face down a dozen snarling big cats, but his methods leave a lot to be desired. There is also a lot of footage of lions and tigers fighting each other, an incredible but unedifying spectacle.