Black Swan is a 2010 American psychological horror film directed by Darren Aronofsky from a screenplay by Mark Heyman, John McLaughlin, and Andres Heinz, based on a story by Heinz. The film stars Natalie Portman in the lead role, with Vincent Cassel, Mila Kunis, Barbara Hershey, and Winona Ryder in supporting roles. The plot revolves around a production of Tchaikovsky's Swan Lake by the company of New York City Ballet. The production requires a ballerina to play the innocent and fragile White Swan, for which the committed dancer Nina Sayers (Portman) is a perfect fit, as well as the dark and sensual Black Swan, which are qualities better embodied by the new rival Lily (Kunis). Nina is overwhelmed by a feeling of immense pressure when she finds herself competing for the role, causing her to lose her tenuous grip on reality and descend into madness.

Psychological horror is a subgenre of horror and psychological fiction with a particular focus on mental, emotional, and psychological states to frighten, disturb, or unsettle its audience. The subgenre frequently overlaps with the related subgenre of psychological thriller, and often uses mystery elements and characters with unstable, unreliable, or disturbed psychological states to enhance the suspense, horror, drama, tension, and paranoia of the setting and plot and to provide an overall creepy, unpleasant, unsettling, or distressing atmosphere.