In the 850s Ketil was a prominent viking chieftain. He conquered the Hebrides and the Isle of Man. Some sources refer to him as "King of the Sudreys" but there is little evidence that he himself claimed that title. The Norwegian king appointed him the ruler of these islands, but he failed to pay tribute to Harald Fairhair and was outlawed. Most of his family eventually emigrated to Iceland.
Ketil's wife was Yngvild Ketilsdattir, daughter of Ketil Wether, a hersir from Ringarike. They had a number of children, including Bjorn the Easterner, Helgi Bjola; Aud the Deep-Minded, and Thorunn the Horned.
Ketil's daughter Aud married Olaf the White, King of Dublin. Their son, Thorstein the Red, briefly conquered much of northern Scotland during the 870s and 880s before he was killed in battle. Aud and many members of her clan settled in the Laxdael region of Iceland.