Bór's people came into Beleriand after the Dagor Bragollach ("Battle of Sudden Flame"). He and his sons Borlad, Borlach, and Borthand swore alligence to Maedhros and Maglor. Bór fell in the Nirnaeth Arnoediad ("Battle of Unnumbered Tears"), fighting the forces of the traitor Ulfang and his sons.
Bór's name comes from the Sindarin word bôr, meaning "faithful vassal". This sobriquet is very similar the name given to Balan, who is better known as Bëor the Old. Balan was a vassal of King Finrod, and the word bëor means "vassal" in Balan's native tongue of Taliska. Unlike Bëor, though, Bór's original name was never recorded.