High School DxD is a Japanese light novel series written by Ichiei Ishibumi and illustrated by Miyama-Zero. The series revolves around Issei Hyoudou, a perverted high school student who is reincarnated into a Devil by Rias Gremory after being killed on his first date. He later joins the Occult Research Club as he strives to rise up the Devils' ranks to fulfill his dream of building a harem and becoming a "Harem King".

High School DxD began serialization in Fujimi Shobo's Dragon Magazine in its September 2008 issue, and the first volume was released in Japan on September 20, 2008. There are currently nineteen volumes available in Japan as of November 20, 2014 sold under Fujimi Shobo's Fujimi Fantasia Bunko imprint.

A manga adaptation illustrated by Hiroji Mishima began serialization in the July 2010 issue of Dragon Magazine, before moving to Monthly Dragon Age, with seven volumes currently sold as of December 9, 2014. A spin-off series by Hiroichi, called High School DxD: Asia and Koneko's Secret Contracts!? (ハイスクールD×D アーシア&小猫 ヒミツのけいやく!? Haisukūru DxD: Āshia ando Koneko Himitsu no Keiyaku!?), centering on Asia Argento's first duties as a Devil, was serialized in Monthly Dragon Age from the October 2011 issue to the April 2012 issue. It was later released as a tankōbon volume on March 9, 2012. A second spin-off series, titled High School DxD: The Work of a Devil (ハイスクールD×D アクマのおしごと Haisukūru Dī Dī: Akuma no Oshigoto), began in the April issue of Monthly Dragon Age. Illustrated by SODA, it adapts the short stories found in the light novels.

An anime adaptation, produced by TNK under the directorship of Tetsuya Yanagisawa, aired twelve episodes in Japan on TV Tokyo's satellite channel AT-X and other networks from January 6, 2012 to March 23, 2012. An OVA 13th episode written by Ishibumi was bundled with the 13th light novel on September 20, 2012 on Blu-ray disc. A second OVA 14th episode also written by Ishibumi was bundled with the limited edition release of the 15th light novel on May 31, 2013.

A second season of High School DxD, titled High School DxD New (ハイスクールD×D NEW Haisukūru Dī Dī Nyū), was announced at the post-end credits of the 13th episode and premiered on AT-X and Chiba TV on July 7, 2013. The second season adapts volumes three and four of the light novels and is split into two arcs: The Excalibur of the Moonlit Schoolyard (ハイスクールD×D3 月光校庭のエクスカリバー Gekkō Kōtei no Ekusukaribā) and the The Vampire of the Suspended Classroom (停止教室のヴァンパイア Teishi Kyōshitsu no Vanpaia). An unaired episode 13 for the second season is set to be release on March 10, 2015 along with the High School DX1. short story compilation.

A third season, High School DxD BorN (ハイスクールD×D BorN Haisukūru Di Di BorN), was announced in June 13, 2014 by Fujimi Shobo with the title and airing date being released at December 6, 2014. High School DxD BorN is set to be aired in April 2015 and will cover the remaining parts of the Birth of the Breast Dragon Emperor arc.

The anime is licensed in North America by Funimation Entertainment and in Australia and New Zealand by Madman Entertainment.