Ikki Tousen (Japanese: 一騎当千, Hepburn: Ikkitōsen, lit. "A Mighty Knight Who Matches a Thousand Knights"), also known as Battle Vixens in North America, is a Japanese manga series written and illustrated by Yūji Shiozaki. Loosely based on the classic 14th century Chinese novel Romance of the Three Kingdoms, the series revolves around an all-out turf war in the Kantō region of Japan where fighters known as Tōshi (闘士, meaning "fighting soldier") from seven schools battle for supremacy. The story centers on Hakufu Sonsaku, a fighter who transfers to Nanyo Academy, one of the seven schools involved in the turf war.

The manga was serialized in the seinen manga magazine Comic Gum from April 2000 to August 2015. The series was collected in 24 tankōbon volumes released between October 2000 and September 2015. The manga was licensed in North America and the United Kingdom by Tokyopop, with adaptation from Keith Giffen under the title Battle Vixens; and in Australia and New Zealand by Madman Entertainment.

The original manga has inspired four anime television series and three OVAs. A 13-episode adaptation animated by J.C.Staff aired between July and October 2003, on AT-X and other channels. It would be followed by a second 12-episode season, subtitled Dragon Destiny, which was animated by Arms and aired on AT-X between February and May 2007. The third and fourth anime series, Great Guardians and Xtreme Xecutor, would deviate from the manga's plot and feature original storylines and new characters. The third season was animated by Arms, and aired on AT-X between June and August 2008; while the fourth anime season was animated by TNK, and aired on AT-X and other channels between March and June 2010; both spanning 12 episodes. The first OVA, Shūgaku Tōshi Keppu-roku, would be released in Japanese theaters on November 12, 2011. The second, two-episode OVA subtitled Extravaganza Epoch was released between December 21, and 28, 2014. A 3-episode OVA, Western Wolves, was released between January and February 2019.

The first anime season was initially licensed in North America by Geneon Entertainment. After Geneon withdrew from the anime market, the season would be re-licensed by Funimation. The second and third seasons were licensed in North America by Media Blasters. Funimation would later re-licensed the third season, while acquiring the fourth.

A sequel manga titled Shin Ikki Tousen began serialization in Shōnen Gahōsha's Young King OURs magazine in November 2015. A three-episode anime adaptation, once again animated by Arms, aired on AT-X in May 2022.