Bathory were a Swedish black metal band formed in Vällingby in March 1983. Named after Hungarian countess Elizabeth Báthory, they are considered pioneers of black metal (alongside Venom and Mercyful Fate) and Viking metal. The book Lords of Chaos described Bathory's first four albums as "the blueprint for Scandinavian black metal." Acts influenced by their early records include Mayhem, Burzum, Darkthrone, Gorgoroth, Satyricon, Emperor, Dark Funeral, Enslaved, Marduk, Moonsorrow and Dimmu Borgir. Bathory abandoned the black metal sound for their fifth record, Hammerheart (1990), which is often cited as the first Viking metal album. Bathory continued in the Viking metal style for most of their remaining existence, although they experimented with a thrash metal style on the albums Requiem (1994) and Octagon (1995). They stopped performing live early on and never toured; frontman, founder and main songwriter Tomas "Quorthon" Forsberg was the sole constant member and at times responsible for all instruments. Bathory ended when Forsberg died from heart failure at the age of 38 in 2004.