"Lady Evil" is the third track on the Black Sabbath album Heaven and Hell. It is written by Ronnie James Dio, Tony Iommi, Bill Ward and Geezer Butler. This song, like others on the album, reflects Dio's poetic turn with the lyrics, which were such a sharp departure from the Ozzy Osbourne-era Black Sabbath. As Tony Iommi mentions in the book Precious Metal: Decibel Presents the Stories Behind 25 Extreme Metal Masterpieces, "None of those songs would have worked with Ozzy."

"Lady Evil" is an example of a song that gave Ronnie James Dio and Black Sabbath a reputation for misogyny. "Digital Bitch," from the Ian Gillan years, is another one. Think what you will of Dio's attitude towards women, but know this: he has married twice, and the second wife is Wendy Galaxiola, who also serves as his manager, and whom he married in the early 1980s and remains married to.
Now for the other half of this title, there is definitely some association between Satanism and heavy metal music, and perhaps this song with its setting in "Witch's Valley" is a good place to examine it. Dio is allegedly the first to throw the "goat's head" (the "horns" made by raising the index and pinkie fingers from the upthrust fist), after all. Now, various music genres have found themselves inextricably linked with certain lifestyles. For instance, Trance music is associated with psychedelics, which prompted hacker-demigod-turned-'Frisco-club-owner Jamie Zawinski to lament the genre's single-mindedness: "There is no such song as 'Acid Acid Acid' by 'The Acid Heads' but there might as well be." Similarly, there is no Heavy Metal song called "Satan's 666 Pentagrams of the Antichrist" by Lucifer's Choirboys - but wouldn't it be cool if there were? Anyway, Dio himself asserts in this interview with HM Magazine that it's all an act! Isn't that right, boys and girls?