History Channel’s Vikings sees many characters die in different circumstances – some in battle, others by betrayal, and some others, like Sigurd Ragnarsson, at the hands of a family member. Created by Michael Hirst, Vikings initially follows the life and adventures of legendary Norse hero Ragnar Lothbrok (Travis Fimmel) and his Viking brothers, from the start of the Viking Age onward. As the series progresses and more characters are introduced, the series shifts its focus to Ragnar’s sons and their journeys, with Ragnar dying in season 4.
https://screenrant.com/vikings-show-season-4-sigurd-death-ivar/