The high captain of Angband and marshal of Morgoth's hosts, accounted the greatest and most dreadful of the Balrogs -- those Maiar whom Melkor had seduced in the deeps of time, and who clothed themselves in shadow and flame. Gothmog wielded a great black axe and led the armies of the Enemy through the wars of Beleriand. In the Dagor-nuin-Giliath, the Battle-under-Stars, he and his Balrogs surrounded Feanor when the fiery spirit of the Noldor pressed too far ahead of his host, and Gothmog dealt him the wounds of which he died within sight of the towers of Thangorodrim.
His deadliest hour came in the Nirnaeth Arnoediad, the Battle of Unnumbered Tears, where he hewed down Fingon, High King of the Noldor, beneath his black axe, and it was at his command that Hurin Thalion was taken alive and dragged captive to Angband. Gothmog met his own end in the Fall of Gondolin: there Ecthelion of the Fountain, lord of the city's guard, grappled with him upon the steps of the king's square, and the two fell together into the great fountain, where the Balrog's flame was quenched and he was slain.