Berserkers appear prominently in a multitude of other sagas and poems, many of which describe berserkers as ravenous men who loot, plunder, and kill indiscriminately. Later, by Christian interpreters, the berserk was even viewed as a "heathen devil."[9]
The earliest surviving reference to the term "berserker" is in Haraldskvæði, a skaldic poem composed by Thórbiörn Hornklofi in the late 9th century in honor of King Harald Fairhair, as ulfheðnar ("men clad in wolf skins"). This translation from the Haraldskvæði saga describes Harald's berserkers: