Blot-Sweyn, a figure shrouded in the mists of history, is believed to have been a Swedish king around the year one thousand eighty. His reign is marked by controversy, particularly regarding his ascension to the throne, which came at the expense of his brother-in-law, Inge. Inge's refusal to perform the blót, the pagan sacrifices at the revered Temple at Uppsala, led to Blot-Sweyn's rise, highlighting the tensions between the old pagan traditions and the encroaching Christian faith.
Despite his claim to the throne, Blot-Sweyn's historical presence is tenuous. Notably, he is absent from the regnal list of the Westrogothic law, suggesting that his influence may not have extended to the region of Västergötland. This absence raises questions about the extent of his rule and the legitimacy of his kingship.
Swedish historian Adolf Schück posits that Blot-Sweyn may have been synonymous with Håkan the Red, indicating that the name 'Blót Swain' was likely an epithet rather than a formal title. This title reflects his willingness to engage in the pagan rituals that were increasingly at odds with the Christianization of Sweden.