Duinir was the lord of the Blackroot Vale in the valley of the River Morthond in the west of Gondor.

He led his two sons, Derufiin and Duilin, along with many of his archers to the Battle of the Pelennor Fields to aid Minas Tirith during the War of the Ring.

Both of his sons were lost in that battle, but of Duinir's fate, we can only guess that he survived, because his name was not listed amongst those lost.