What is "antikiller"

Antikiller is a 2002 Russian crime film directed by Egor Konchalovsky. It portrays a brutal war between obnoxious crime gangs and a one-man vigilante, a former police officer. The movie is based on Daniil Koretsky’s novel of the same name, which has sold five million copies in the countries of the former Soviet Union and has acquired cult status among readers of Russian pulp fiction. Like the novel, the film became the box office leader among Russian films in 2002.