Mona Demarkov is a sociopathic Russian mob assassin and main antagonist in the 1993 crime film Romeo is Bleeding. She is played by Lena Olin.
The head of the Italian mob, Don Falcone, orders Jack to deal with Demarkov or face dire consequences. Jack is unable to kill her; she even seduces and makes a fool of him. Falcone, disappointed in Jack's ineptitude, orders one of Jack's toes cut off. Seriously injured due to the amputation and realizing that he has endangered his wife and mistress, Jack instructs his wife to leave the city immediately, giving her money and instructions where to meet him out West when the time is right. Jack also ends his affair with his mistress and puts her on a train out of the city. Jack tries to hunt Demarkov but soon realizes that he is putty in her hands. He is attracted to her sexually and no match for her professionally. Mona offers to pay Jack to help her eliminate Falcone and fake her own death. Although he obtains phony papers for her, she refuses to pay and attempts to strangle him. He shoots and seriously wounds her, then tries to drive away with her handcuffed in the back seat. Mona escapes by hooking her legs around his neck, causing him to crash the car. She slithers out through the shattered windshield without ever freeing her hands. Mona lures Jack to an abandoned warehouse. He again attempts to kill her but is tricked into shooting Sheri instead. Mona fixes the corpse so as to suggest that it was she, and not Sheri, who died. (Her scheme involves severing her own arm and substituting it for Sheri's.) Mona then handcuffs Jack to the bed and has her way with him. Asking Jack, "with or without", he replies "without" and she mounts him after unbuckling her new prosthetic arm, her last concession to conventional appearances. Demarkov then forces Jack to kill Don Falcone, burying him alive, even after having her arm replaced with a prosthetic. She proceeds to turn in Jack to the police, his former associates, copping a plea deal that will indict Jack for the multiple murders that she tricked him into committing. The police arrange a confrontation between Jack and Demarkov at the courthouse, as he is heading in and she is heading out. She threatens to kill his wife. Thinking he has nothing to lose, and desperate to save the only thing good in his life, Jack grabs a gun from the ankle holster of a fellow officer and shoots her down. Jack turns the gun on himself, only to discover that the revolver is empty. Instead of being sent to prison for the murder, he is given a commendation. This frees him to begin a new life out West in a remote town. He waits at the appointed time and place, imagining Natalie's return to him, but her forgiveness is only in his mind.