Kazushi Hagiwara is an enthusiastic fan of heavy metal music and Dungeons & Dragons, using ideas from both of these in the Bastard!! story. Many characters and places in the story, for instance, are named after members of Hagiwara's favorite bands. Hagiwara also attributes the manga Devilman by Go Nagai as a primary influence on his artwork.

The manga is published in English by Viz Media. Only volumes 1–19 have been translated, with no plans to release the rest. Additionally, a six-part anime OVA was released in 1992. The OVA was released in North America by Pioneer in 1995. Bastard!! is one of Weekly Shōnen Jump's best-selling manga series of all time, with over 30 million copies sold by 2008.