The episodes from X anime television series are based on Clamp's manga with the same name. The series was produced by Madhouse and directed by Yoshiaki Kawajiri, being first announced on October 18, 2000. The story takes place at the end of days, in the year 1999. The series follows Kamui Shirō, a young esper who returns home to Tokyo after a six-year absence to face his destiny as the one who will determine humanity's fate.
In anticipation to the series premiere, X: An Omen (エックス - 前兆 Ekkusu - Yochō) was released direct-to-DVD on August 25, 2001. Written and directed by Kawajiri, "An Omen" tells the story of the upcoming battles through the prophecies of Kakyō Kuzuki, dreamgazer for the Dragon of Earth, and acts as primer for viewers not familiar with Clamp's manga. The series premiered October 3, 2001 on WOWOW satellite television and finished on March 27, 2002, totaling twenty-four episodes. A total of twelve DVD volumes from the series, each containing two episodes, were released in Japan from February 25, 2001 to January 25, 2002 by Bandai Visual.
The series was first licensed in North America by Pioneer Entertainment in March 2002.Geneon collected the series and the OVA in a total of eight DVD volumes released between September 24, 2002 and November 25, 2003. Two DVD box sets of the series were also released on January 11, 2005. In 2006, Geneon released the X TV Series Remix, which was composed of five individual DVDs released between July 11, 2006 and November 14, 2006, as well as a DVD box set on July 11, 2006. The DVDs came with re-encoded video and audio, including 5.1 surround sound for both the Japanese and English tracks. In September 2009, Funimation Entertainment announced that it had acquired the rights to the anime series and OVA. They were re-released them in a DVD box it on June 15, 2010 using the original Geneon dubbing (provided by Bang Zoom! Entertainment) for the English-language audio track.