Ichi the Killer (Japanese: 殺し屋１, romanized: Koroshiya Ichi, lit. 'Hitman One') is a 2001 Japanese horror yakuza film directed by Takashi Miike, written by Sakichi Sato, and starring Tadanobu Asano and Nao Omori. Based on Hideo Yamamoto's manga series of the same name, its plot follows a psychologically damaged man who is manipulated into assaulting or killing rival faction members of feuding yakuza gangs while being pursued by a sadomasochistic enforcer.

The film has garnered controversy due to its graphic depictions of violence and cruelty and was subject to censorship in several countries.