Question: Who was a famous band member for both Haven and Mercyful Fate?

Context paragraphs:
Melissa (Mercyful Fate album): Melissa is the debut studio album by Danish heavy metal band Mercyful Fate, released on 30 October 1983.  It was the first album released by Roadrunner Records.  This was also the first Mercyful Fate effort to get an official release in the United States through Megaforce Records, as the self-titled EP was a highly sought after import, and the BBC sessions were only available on bootleg tapes.

Mercyful Fate discography: The discography of Mercyful Fate, a Danish heavy metal band, consists of seven studio releases, three compilations, three singles, and six music videos. Mercyful Fate was formed in 1981 by vocalist King Diamond and guitarist Hank Shermann.  After several line-up changes and self-made demos, Mercyful Fate released their self-titled EP in 1982, with the line-up of King Diamond (vocals), Hank Shermann (guitar), Michael Denner (guitar), Timi Hansen (bass) and Kim Ruzz (drums).  With this line-up, the group released their debut album, "Melissa", on October 30, 1983, through Roadrunner Records.  The following year, Mercyful Fate recorded their second album "Don't Break the Oath".  Released on September 7, 1984, the album debuted at number 33 on the Swedish Sverigetopplistan charts.  Despite winning a cult following around the world, Mercyful Fate broke up in April 1985, due to musical differences.

Dead Again (Mercyful Fate album): Dead Again is the sixth studio album by Mercyful Fate, released in 1998 by Metal Blade Records.  It marks the first album from Mercyful Fate that Michael Denner is not present on.  It also marked a new era for the band, as the production is more muddy and raw, and the guitar tone is more distorted than on the three previous albums.  In addition, the album introduced a more complex and arguably progressive sound to several of its tracks.

King Diamond: Kim Bendix Petersen (born 14 June 1956), better known by his stage name King Diamond, is a Danish heavy metal musician.  As a vocalist, he is known for his extensive vocal range, in particular his usage of falsetto.  He is the lead vocalist for both Mercyful Fate and the eponymous King Diamond.

The Best of Mercyful Fate: The Best of Mercyful Fate is a compilation album by the band Mercyful Fate from years 1982-1984.

King Diamond (band): King Diamond is a Danish heavy metal band formed in 1985 by vocalist King Diamond, guitarists Andy LaRocque and Michael Denner, bassist Timi Hansen and drummer Mikkey Dee.  Diamond, Denner and Hansen had recently departed the group Mercyful Fate, and decided to form a new band under the King Diamond moniker, as it was already known from the Mercyful Fate days.  In 1986, King Diamond released their debut album "Fatal Portrait".  Since then the band have released a total of twelve studio albums (most of them concept albums), two live albums, two extended plays, five compilations and five singles.

Haven (American band): Haven was a Christian progressive metal band from [New Jersey] during the late 1980s until 1993.  Haven drew its influences from bands such as, Queensrÿche, Metallica, King Diamond, and Dream Theater.  Haven split shortly after the completion of the "Age of Darkness" release.

Force of Evil (band): Force of Evil was a Danish 5-piece heavy metal band formed by the twin guitarists of Mercyful Fate, Michael Denner and Hank Shermann.  They joined forces with Hal Patino, Bjarne T. Holm and Martin Steene, all known for their performance with King Diamond, Mercyful Fate and Iron Fire.

In the Shadows (album): In the Shadows is the third full-length studio album by Mercyful Fate.  It is also the first offering of the band since their reunion in 1992.  It was released in 1993 on Metal Blade Records.  Unlike previous Mercyful Fate albums, which were entirely centered around lyrical themes of Satanism and the Occult, the lyrics on this album are rather focused on more conceptual horror-themes, akin to King Diamond's work with his eponymous band.  The band would not return to a primarily occult/Satanic lyrical approach until the band's final album, 9, released in 1999.

Mercyful Fate: 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, with lyrics dealing with Satan and the occult, Mercyful Fate were part of the first wave of black metal in the early to mid-1980s.  Many of the bands from this movement went on to influence later black metal musicians in the 1990s, particularly in Norway.  Since the band's inception in 1981, Mercyful Fate have released seven studio albums, two extended plays and four compilations.

Supporting paragraphs: Haven (American band) King Diamond
Answer: King Diamond