Blade of the Immortal (Japanese: 無限の住人, Hepburn: Mugen no Jūnin, lit. 'The Inhabitant of Infinity') is a Japanese manga series written and illustrated by Hiroaki Samura. It was serialized in Kodansha's seinen manga magazine Monthly Afternoon from June 1993 to December 2012, with its chapters collected in 30 tankōbon volumes. The series is set in Japan during the mid-Tokugawa Shogunate period and follows the cursed samurai Manji, who has to kill 1,000 evil men in order to regain his mortality.

A 2008 anime television series adaptation was produced by Bee Train. Also in 2008, the novel Blade of the Immortal: Legend of the Sword Demon was released by Kodansha. A live action film adaptation of the same name was released in April 2017. A second anime adaptation by Liden Films was broadcast from October 2019 to March 2020. In North America, the manga has been published by Dark Horse Comics. The first anime series was licensed by Media Blasters. The second anime series is licensed by Amazon Prime Video.

By May 2019, the manga had over 7.5 million copies in circulation. In 1997, Blade of the Immortal received the Excellence Award at the first Japan Media Arts Festival.