Underworld is a 2003 action horror film directed by Len Wiseman and written by Danny McBride, based on a story by McBride, Kevin Grevioux, and Wiseman. The film centers on the secret history of vampires and lycans (an abbreviated form of lycanthrope, which means werewolf). It is the first (chronologically, the second) installment in the Underworld franchise. The main plot revolves around Selene (Kate Beckinsale), a vampire Death Dealer hunting Lycans. She finds herself attracted to a human, Michael Corvin (Scott Speedman), who is being targeted by the Lycans. After Michael is bitten by a Lycan, Selene must decide whether to do her duty and kill him or go against her clan and save him. Alongside Beckinsale and Speedman, the film stars Michael Sheen, Shane Brolly, and Bill Nighy.
An international co-production between companies from the United Kingdom, Germany, Hungary, and the United States, the film was released on September 19, 2003. Upon its release, the film received generally negative reviews from critics, but a smaller number of reviewers praised elements such as the film's stylish Gothic visuals, the "icy English composure" in Kate Beckinsale's performance, and the extensively worked-out vampire-werewolf mythology that serves as the film's backstory. A surprise hit, the film grossed $95 million against a production budget of $22 million. The film was followed by Underworld: Evolution, released three years later, and by three other films.