An Icelandic musician and actor, he is best known as the bassist for the post-rock band Sigur Rós. Born in 1976, he co-founded the band in 1994 alongside Jónsi Birgisson and Ágúst Ævar Gunnarsson. While his primary focus remains music, he has occasionally ventured into acting, contributing to the artistic and experimental nature of the group's visual projects. His work has significantly influenced the ambient and post-rock music scenes.