Black Swanis a 2010 American psychological thriller film directed by Darren Aronofsky and starring Natalie Portman , Vincent Cassel , and Mila Kunis . Its plot revolves around a production ofSwan Lakeby a prestigious New York City ballet company. As is usual with all productions of the ballet, the production requires a ballerina to play both the innocent White Swan and the sensual Black Swan. One dancer, Nina (Portman), is a perfect fit for the White Swan, while Lily (Kunis) has a personality that matches the Black Swan. When the two compete for the parts, Nina finds a dark side to herself.

Aronofsky conceived the premise by connecting his viewings of a production ofSwan Lakewith an unrealized screenplay about understudies and the notion of being haunted by a double, similar to the folklore surrounding doppelgängers . The director also consideredBlack Swana companion piece to his 2008 filmThe Wrestler, with both films involving demanding performances for different kinds of art. He and Portman first discussed the project in 2000, and after a brief attachment to Universal Pictures,Black Swanwas produced in New York City in 2009 by Fox Searchlight Pictures . Portman and Kunis trained in ballet for several months prior to filming and notable figures from the ballet world helped with film production to shape the ballet presentation. The film premiered as the opening film for the 67th Venice International Film Festival on September 1, 2010. It had a limited release in the United States starting December 3, 2010 and a nationwide release on December 17.

A New York City ballet company is preparing for the production ofSwan Lake, choosing to cast a new lead to replace current star Beth MacIntyre as the Swan Queen. However, the lead must maintain an adequate portrayal of both the White and Black Swans. Nina Sayers, a dancer, is picked to compete for the part alongside several other young dancers, including newcomer Lily. Nina lives with her caring but overbearing mother Erica, a failed dancer turned amateur artist who tries to control much of Nina's life.

The ballet director Thomas Leroy, is reluctant to cast Nina; he claims that she is the perfect White Swan, with perfect technique, but that she lacks the passion of the darkly sensual Black Swan. During a confrontation over the role, Thomas kisses her, and she bites his lip, surprising and exhilarating him; directly after, he casts her in the lead, even though he had claimed Veronica, another girl competing for the part, was getting the part. He presents her as his new star during a benefit gala. After the gala, when Nina is leaving, Thomas catches up with her and offers for her to come back to his apartment for a while, Nina hesitantly accepts and then waits for him in the entrance hall as he says his goodbyes. Nina sees a sculpture of a person with no arms and skeletal features made from a dark metal, with stubby wings growing from each shoulder blade. This somehow shows a significance to Nina as she looks at it intensely for a moment, when she turns she finds herself face to face with a drunken Beth who has obviously been crying. Beth starts accusing Nina of gaining the part as the prima ballerina from sexually pleasing Thomas. Nina is shocked and begins to walk away as Thomas runs in to calm down Beth, who pushes him away shouting. Thomas comes over to Nina trying to reassure her that it was ok.

Nina displays a number of psychotic symptoms, including strong delusions and elaborate visual hallucinations . She begins to feel paranoid that Lily, her understudy, is determined to take the lead away from her. Thomas, meanwhile, becomes increasingly critical of Nina's "frigid" dancing as the Black Swan, and tells her that she should stop being so perfect and simply lose herself in the Black Swan role.

One night, Lily appears at Nina's door and invites Nina to go out on the town with her. Nina is at first reluctant, but after her mother's pushiness to get rid of Lily, she quickly leaves to escape her controlling mother. During the night out, she takes drugs and becomes more interested in Lily than the men at the bar. Upon returning to Nina's apartment with Lily, the two have sex after Nina and her mother have an enraged argument. Nina wakes up alone the next morning, and rushes to make it on time to rehearsal. When she enters the studio, she finds Lily dancing as the Swan Queen in her absence. Furious, Nina confronts Lily, and asks her why she did not wake her up in the morning. Lily states that she spent the night with a man whom she met at the club, and teases Nina for fantasizing about her.

The night before the ballet's opening, Nina is rehearsing late and continues to experience strong visual hallucinations, such as her reflection acting independent of her and of Lily and Thomas having sex together backstage. When she returns home, she sees her mother's paintings speaking and mocking her. She also notices that the rash on her shoulder has worsened, with little black barbs poking through her skin. Nina pulls one of the barbs from her skin, and it appears to be a black feather. Nina's eyes appear to turn into reddish swan eyes and her legs violently contort into the shape of a swan's. As she tries to steady herself, she falls and knocks herself out on her bedpost.

Nina awakes the night of the opening performance, locked in her bedroom with her mother. Nina's mother tells her that she called the company and informed them that Nina wasn't feeling well and will not be able to perform. After violently forcing her mother to let her leave, Nina arrives at the theater and immediately prepares herself as the White Swan.

The first act goes poorly; the Prince drops Nina while dancing onstage. Distraught, Nina returns to her dressing room and finds Lily there, dressed in the Black Swan costume. As Lily announces her intention to play the Black Swan, she changes form into Nina herself. Nina and her duplicate wrestle, with Nina shoving her into a full-length mirror, and during the ensuing scuffle, takes a shard of the mirror and stabs her duplicate, killing her. Upon realizing what she has done, she sees that the body is Lily's. After hiding Lily's body, Nina returns to the stage and dances the Black Swan (the third act ofSwan Lake), passionately and sensually, growing black feathers all over her body as she dances, her arms becoming black wings as she finally loses herself and transforms into a black swan; at the end of the act, she receives a standing ovation. When she leaves the stage, she finds Thomas and kisses him with seductive power for the first time.

Back in her dressing room, she is interrupted by a knock at her door and opens it to see Lily, who has come to congratulate her. Nina realizes the fight was another hallucination; however, the mirror is still shattered. She notices a wound on her body and realizes that she apparently stabbedherselfas the White Swan, not Lily. Back on stage, Nina dances passionately and seamlessly in the fourth and final act as the White Swan. In the last moments of the ballet, when the Swan is supposed to kill herself by jumping off a cliff on the stage, the audience erupts in thunderous applause while the cast discovers Nina lying on the safety mattress backstage. After Thomas enthusiastically congratulates her on her performance, Lily gasps in horror as she, Thomas, and the cast see that Nina is covered in blood. Though Nina lies wounded and perhaps dying, she feels content that everything she went through helped her to achieve a perfect performance. The film draws to a close with Nina staring up at the stage lights while whispering "I felt it. Perfect. I was perfect.", as the screen fades to white and the audience chants her name.