A Dunadan Warrior from Sarn Erech in Morthond Fief in Lamedon, Duilin was the older son of Duinhir. He and his brother Derufin each commanded a company of bowmen in the force of 500 men led by their father at the Battle of Pelennor Fields in T.A. 3019. Like Derufin, Duilin perished in the attack against the Mumakil (Oliphaunts).