Bereg (F.A. 340) was a great-grandson of Bëor the Old, who led the unrest of Men at their camps at Estolad. IN F.A. 365 he led a thousand Men of the House of Bëor away southwards out of Beleriand.
His and his followers' fate is not known, but presumably they reached Eriador and merged with the Pre-Númenórean peoples there.