Maniac (1934)

Starring Bill Woods, Horace Carpenter, Ted Edwards, Phyllis Diller, Thea Ramsey
Directed by Dwain Esper
(actor & director credits courtesy IMDB.com)

When a mad scientist exhorts his assistant to kill himself so that he can bring him back to life, the assistant instead kills the scientist, and impersonates him while descending into madness.

In between title cards defining various mental psychoses, not all of which may be portrayed in the movie, Esper, a director of low-budget films on sensationalist topics, stages his horrific drama, inserting flashes of nudity and disturbing violence.  Frankenstein was clearly an inspiration with the subject matter of bringing the dead back to life at the forefront, and a story detail is borrowed from Edgar Allan Poe's The Black Cat, but the overall plot seems pretty much window dressing for scenes in which Esper tries to shock his audience.  Cat lovers may well be deeply disturbed by some dialogue involving a "cat and rat farmer," as well as a horrific scene involving a feline eyeball, which I was relieved to later read was not real.  The film still has the power to shock, so I'll give Esper that, although if he was attempting a serious treatise on madness, he falls greatly short, and there's plenty of flat dialogue readings and a number of scenes that could be considered laughable.  The picture is however certainly unique and watchable, at least I thought so.