Tomas Börje Forsberg, known by the stage name Quorthon (17 February 1966 – c. 3 June 2004), was a Swedish musician. He was the founder and songwriter of the band Bathory, which pioneered the black metal genre and is credited with creating the viking metal style. A multi-instrumentalist, Quorthon wrote the music and lyrics on all of Bathory’s albums and performed vocals and guitars.

Quorthon formed Bathory in 1983 when he was 17 years old, after briefly playing in the Oi! band Stridskuk. He recorded his early albums together with the help of Börje Forsberg, the head of the Swedish record label Tyfon Grammofon, who also released most of his albums on the Tyfon imprint Black Mark. The first album was recorded in the garage of famed schlager writer Peter Himmelstrand, dubbed Studio Heavenshore.

Around this time (in the mid- to late 80s) live performances by Bathory were rare. Albums from this period helped the then-burgeoning black metal subgenre, and rare photographs of the band helped in part to define its image. Beginning in the 1990s, Quorthon took full control of Bathory, choosing to forgo performing live in order to spend time recording music with hired musicians, as well changing style from the black metal of the 80’s to a slower, heavier style dubbed “Viking metal”, due to its lyrics being focused on Norse mythology. From this point onwards, he also played bass guitar on almost all of his albums, and mostly used a drum machine or a session drummer.

Quorthon also personally paid for the production of Bathory’s only ever music video, for the song “One Rode to Asa Bay”, taken from their second Viking metal album, Hammerheart. The video was shown on MTV’s Headbanger’s Ball, though Quorthon had not yet seen it at the time he was interviewed for the program.

In 1993 Quorthon set Bathory aside and recorded and released two albums under the name “Quorthon”. The first, called Album, was released in 1994. The final two solo releases emerged in 1997, Purity of Essence and the EP When Our Day Is Through. The albums released under the Quorthon moniker were more rock-oriented than Bathory’s black/viking metal style. While working on these albums he found new inspiration to continue composing music for Bathory. Bathory’s next albums were in a retro-thrash metal style, before he veered towards his Viking metal style once again, especially on the Nordland saga.