Question: Det som engang var (Norwegian for "what once was") is the second studio album by the Norwegian black metal solo project Burzum, a music project that began in 1991, by which Norwegian musician and writer?
Context: Aske (Norwegian for "ashes") is an EP by Norwegian black metal solo project Burzum.  Though recorded in April and August 1992, after "Det som engang var", it was released before that album in March 1993, through Deathlike Silence Productions. From the Depths of Darkness is a compilation album by one-man musical project Burzum, released on 6 December 2011 through Byelobog Productions.  It consists of newly re-recorded tracks from Burzum's first two albums, "Burzum" (1992) and "Det som engang var" (1993), along with three new tracks. Varg Vikernes (] ; born Kristian Larsson Vikernes, 11 February 1973; legally Louis Cachet) is a Norwegian musician and writer.  In 1991, he founded the one-man music project Burzum, which is considered one of the most influential black metal acts.  Three years later, he was convicted of murder and arson, and subsequently served over 14 years in prison. Hvis lyset tar oss (Norwegian for "If the Light Takes Us") is the third studio album by Norwegian black metal solo project Burzum.  It was recorded in September 1992, but was not released until April 1994, whereupon it was released through Misanthropy Records and Vikernes' own record label, Cymophane Productions.  The album is considered a classic in the black metal scene. Burzum ( ; ] ) is a music project that began in 1991 by the Norwegian musician and writer Varg Vikernes.  It became a part of the early Norwegian black metal scene and is considered to be one of the most influential acts in black metal. Fire Walk with Us!  is the second studio album by the industrial black metal band Aborym.  This is Aborym's first album to feature Mayhem vocalist Attila Csihar as a full-time member.  "Fire Walk with Us!"  contains a cover of Burzum's Norwegian: "“Det som en gang var”" , in which bassist Malfeitor Fabban performs vocals. Burzum is the first studio album by Norwegian black metal solo project Burzum.  It was released in March 1992, through Deathlike Silence Productions. Det som engang var (Norwegian for "what once was") is the second studio album by the Norwegian black metal solo project Burzum.  It was recorded in April 1992 and released in August 1993 through Burzum's own label, Cymophane. Strid is a Norwegian black metal band that was originally known as "Malfeitor" from 1991 to 1992.  After releasing two demos - "Malfeitor" (in 1991) and "Pandemonium" (in 1992), they changed their name to "Battle" and there were some line up changes at the time.  In the year of 1992 the band released the "End of Life" demo.  The demo contains only one song which is around 11 minutes.  The line up at the time of recording the demo was: Storm - on bass and vocals, Lars Fredrik Bergstrøm - on guitars and Jardar - on drums.  The guitars were written by Lars Fredrik Bergstrøm (1974 - 2014).  In 1993 the band changed the name to "Strid" which means "Battle" in Norwegian.  That same year, Strid re-released their "End of Life" demo under their new name, through the German label "Malicious Records".  After releasing the "End of life" demo, Lars Fredrik Bergstrøm left the band and was replaced by Ravn Harjar.  Through the years between 1993 and 1995, the band writes and records the self-titled EP which was released through Malicious Records and contains only two songs - "Det hviskes blant sorte vinder" which means "It Is Whispered Amid the Black Winds" in Norwegian and "Nattevandring" which means "Nightwandering" in Norwegian.  The music style and sound of this demo is more ambient/atmospheric black metal oriented.  Mainly because of this release, the band is commonly recognised as the creators of depressive black metal along with some other bands from the second wave of black metal music.  At this time the band line up contains: Ravn Harjar - on guitars, Storm - on bass and vocals and Jardar - on drums.  After the releasing of the self-titled EP, there was no any official releases by the band.  There are also bootleg releases that came out through the years like the CD from 2005 by Ars Mysteriorum and LP, each featuring both "End of Life" and the self - titled EP tracks.  In the year of 2001 the original former member of "Malfeitor/Battle/Strid", bass player and vocalist - Storm committed suicide.  In the year of 2007, the Greek label Kyrck Productions & Armour re-released all the previous material released by the band from the past which contains all "Malfeitor/Battle/Strid" material.  Somewhere between 2009 and 2010 there was a reunion of the band with old members including Vicotnik (Dødheimsgard, ex-Aphrodisiac, ex-Ved Buens Ende, ex-Manes, ex-Code, ex-Naer Mataron, ex-Endwarfment).  Another member that was part of the reunion was Lars Fredrik Bergstrøm - the main composer of the "End of Life" track.  In 2014 Lars Fredrik Bergstrøm died.  At this time the band line up contains Ravn Harjar - on guitars and vocals, Vicotnik - on bass and Sigmund (ex-Inflabitan, ex-Dødheimsgard) - on guitars.  In January 2015, Ravn Harjar wrote a statement on the official Strid Facebook page that in the autumn of the year 2015 the band will start recording their first full-length album which will be titled "Endetid".  That means "End of times" in Norwegian. Filosofem (Norwegian for "philosopheme") is the fourth studio album by Norwegian black metal solo project Burzum.  It was recorded in March 1993 and was the last recording before Varg Vikernes' imprisonment (16 May 1994); the album was not released until January 1996, however.  A music video was made for the song "Dunkelheit", which received airtime on both MTV and VH1.
Answer: Varg Vikernes