Man with the Screaming Brain

A wealthy U.S. drug company CEO who travels to Bulgaria seeking new markets. He is portrayed as the stereotypical 'ugly American' who dismisses the local scene, driven by money and control. After the brain swap with Yegor, he must navigate a merged consciousness while pursuing love and revenge, altering his priorities and sense of self.

William's wife, whose affair with Yegor triggers a chain of violence. Her brain is later transferred into Tatoya's body, creating a Robo-Jackie persona whose actions reflect both affection and avarice. She remains a driving force in the vendetta and eventual reconciliation with William.

A Gypsy woman who kills men who date her and gradually becomes entangled in the central brain-and-ring conflict. She seizes control of William's money and ring, and她 is responsible for key eliminations, including Yegor. Tatoya's cunning drives the pursuit and climactic confrontations around town.

A former KGB agent who manipulates William with a ring and later becomes a vocal presence inside William's head after his brain is transplanted. He guides, criticizes, and complicates William's actions as their minds share one body. His death at Tatoya's hands is a pivotal moment before the brain is fully reconciled.

Bulgarian scientist leading the brain transplant process, aided by an assistant. He orchestrates the surgical reshaping that allows William and Jackie to persist in altered bodies. His role is pivotal in the science-driven backbone of the plot, and he is later involved in efforts to repair the restored pair.

Ivanov's idiotic assistant who helps with the surgeries. His bumbling nature provides some comic relief amidst the chaos of the experiments, yet he remains a functional participant in the plot's technical side. Pavel's presence highlights the human element behind extraordinary procedures.