
Arthwail (841-885) was a nobleman of Gliwissig during the late 9th century AD. He was presumably the uncle of King Owin of Gliwissig, and he was declared Owin's heir due to his inability to sire children. Arthwail led an army against Gwent during the Welsh Rebellion of the 880s, but his force was resoundingly defeated by King Bledri of Gwent; Arthwail escaped to Dinas Powis with only 19 of his men. In 885, the West Saxon nobleman Aethelhelm marched on Gliwissig after subduing Gwent (which had belatedly joined the rebellion), and he laid siege to the village of Dinas Powis. As the city was held by just 19 defenders, including Arthwail, Aethelhelm used his superior numbers to massacre Arthwail and the defenders.