High School DxD (Japanese: ハイスクールD×D, Hepburn: Haisukūru Dī Dī) is a Japanese light novel series written by Ichiei Ishibumi and illustrated by Miyama-Zero. The story centers on Issei Hyodo, a perverted high school student from Kuoh Academy who desires to be a harem king and is killed by his first date, revealed to be a fallen angel, but is later revived as a devil by the red-haired devil princess Rias Gremory to serve her and her devil family. Issei's deepening relationship with Rias proves dangerous to the angels, the fallen angels, and the devils. High School DxD began serialization in Fujimi Shobo's Dragon Magazine in its September 2008 issue. The first volume was released on September 20, 2008. A total of twenty five volumes is available in Japan as of March 2018 under their Fujimi Fantasia Bunko imprint. A manga adaptation by Hiroji Mishima began serialization in the July 2010 issue of Dragon Magazine and later in the March 2011 issue of Monthly Dragon Age with eleven volumes released.

An anime adaptation by TNK aired on TV Tokyo's satellite channel AT-X and other networks from January 6 to March 23, 2012. The anime is licensed in North America by Crunchyroll, in the United Kingdom by Manga Entertainment, and in Australia by Madman Entertainment. A second season called High School DxD New (ハイスクールD×D NEW, Haisukūru Dī Dī Nyū) aired from July 7 to September 22, 2013. A third season called High School DxD BorN (ハイスクールD×D BorN, Haisukūru Dī Dī Bōn) aired from April 4 to June 20, 2015. A fourth season called High School DxD Hero (ハイスクールD×D Hero, Haisukūru Dī Dī Hīrō) aired from April 10 to July 3, 2018.