Mr. Crowley

Written by Osbourne, guitarist Randy Rhoads and bass guitarist/lyricist Bob Daisley, it was released on Osbourne's debut solo album Blizzard of Ozz in September 1980 in the United Kingdom.

It was inspired by Aleister Crowley's book Diary of a Drug Fiend that Osbourne had read, and a deck of tarot cards found in the studio as recording of the album was commencing.

Crowley was an English occultist and ceremonial magician who had founded the Thelemite religion in the early 20th century.

The official guide to the video game Fallout 3 uses the lyrics to the song in its walkthrough of You Gotta Shoot 'em in the Head.

The song was included in Guitar Hero World Tour, along with "Crazy Train" and an in-game avatar of Ozzy himself, who becomes unlocked as a playable character upon completing both songs in the vocalist career, and was made available to download on 31 May 2011 for play in the Rock Band 3 music gaming platform in both Basic rhythm, and PRO mode.