Domnall Gerrlámhach (died 1135), also known as Domnall Gerrlámhach Ua Briain, Domnall mac Muirchertaig, and Domnall Ua Briain, was an obscure twelfth-century Uí Briain dynast and King of Dublin. He was one of two sons of Muirchertach Ua Briain, High King of Ireland. Domnall's father appears to have installed him as King of Dublin in the late eleventh- or early twelfth century, which suggests that he was his father's successor-designate. Although Domnall won a remarkable victory in the defence of the Kingdom of Dublin in the face of an invasion from the Kingdom of Leinster in 1115, he failed to achieve the successes of his father. After his final expulsion from Dublin at the hands of Toirdelbach Ua Conchobair, King of Connacht, and the death of his father, Domnall disappears from record unt