Tomas "Ace" Börje Forsberg (often called Quorthon;born on 17 February 1966 in Sweden) was a Swedish musician. He was the founder and songwriter for the extreme metal band Bathory. Bathory was known for laying out the groundwork for black metal and later viking metal. Quorthon was a multi-instrumentalist. He wrote all the music and lyrics for Bathory, and on some albums he played all the instruments (guitar, bass, drums, etc.). He also made solo albums. Quorthon died around 3 June 2004 in Stockholm, Sweden. He died of heart failure.
- Johannesson, Ika & Klingberg, Jon Jefferson. (2011) Blod Eld Död - En svensk metalhistoria, Alfabeta Bokförlag AB, p. 51-68.
- D'Amico, Giuliano. Requiem. Ad un anno esatto dalla morte di Quorthon celebriamo l`imprescindibile combo svedese, Kronic, 7 June 2005. Accessed 15 February 2012.
- Kouroupis, Panagiotis. Quorthon (Bathory), Blackmore's Night, Megadeth, Sentenced, Avopolis, 15 June 2004. Accessed 15 February 2012.
- Bathory Portrait, musik-base.de. Accessed 15 February 2012.