Jacques Tourneur’s Cat People (produced by Val Lewton) is a landmark of psychological and supernatural horror. Starring Simone Simon, the film follows a Serbian immigrant haunted by fears she will transform into a panther when aroused, blending repression, desire, and fear into an atmospheric classic. Celebrated for its shadows and suggestion, it remains one of horror’s most influential films.

Criterion Collection

The first of the horror films producer Val Lewton made for RKO Pictures redefined the genre by leaving its most frightening terrors to its audience’s imagination. Simone Simon stars as a Serbian émigré in Manhattan who believes that, because of an ancient curse, any physical intimacy with the man she loves (Kent Smith) will turn her into a feline predator. Lewton, a consummate producer-auteur who oversaw every aspect of his projects, found an ideal director in Jacques Tourneur, a chiaroscuro stylist adept at keeping viewers off-kilter with startling compositions and psychological innuendo. Together, they eschewed the canned effects of earlier monster movies in favor of shocking with subtle shadows and creative audio cues. One of the studio’s most successful movies of the 1940s, Cat People raised the creature feature to new heights of sophistication and mystery.

Från IMDB:
An American man marries a Serbian immigrant who fears that she will turn into the cat person of her homeland's fables if they are intimate together.