Arthad was an Adan of the First House, and one of
the last twelve
companions of Barahir in Dorthonion. The twelve outlaws were:
Beren, Baragund, Belegund, Radhruin, Dairuin, Dagnir, Ragnor, Gildor,
Gorlim, Arthad, Urthel, and Hathaldir.
Arthad was slain when Sauron's Orcs surprised the
Men of Dorthonion in
the early hours.
He is remembered in song.
Reference: The Silmarillion