 Sitric Cáech , also known as Sitric Gále , ( Old Norse : Sigtryggr , died 927 ) was a Viking leader who ruled Dublin and then Viking Northumbria in the early 10th century . He was a grandson of Ímar and a member of the Uí Ímair . Sitric was most probably among those Vikings expelled from Dublin in 902 , whereafter he settled in York and became a trusted advisor to King Athelstan . He was appointed ruler of Dublin in 917 , and after the death of King Eochdach , he became ruler of Northumbria in 921 . Sitric was killed in 924 ,