Mercyful Fate is a Danish heavy metal band from Copenhagen, formed in 1981 by vocalist King Diamond and guitarist Hank Shermann. Influenced by progressive rock and hard rock, and with lyrics dealing with LaVeyan Satanism and the occult, Mercyful Fate was part of the first wave of black metal in the early to mid-1980s, along with Venom and Bathory. The band is also cited as a formative influence on many then-up-and-coming subgenres of heavy metal, including thrash metal and death metal, as well as the Norwegian black metal scene.

Kim Bendix Petersen, better known by his stage name King Diamond, is a Danish rock musician. As a vocalist, he is known for his powerful and wide-ranging countertenor singing voice, in particular his far-reaching falsetto screams. He is the lead vocalist and lyricist for both Mercyful Fate and the eponymous King Diamond. He also plays keyboards and guitars on studio recordings but uses live shows to focus solely on his vocal performance. Diamond is renowned for his dark lyrical content and his story concepts. He is also known for his distinctive shock stage persona. He has been an influence for other rock and metal artists, including Metallica, Slayer and Cradle of Filth.