Ulfang the Black

Though the betrayal of the Noldor by Ulfang's people was unquestionably driven by Ulfang himself, there's no mention of his being present at the Nirnaeth Arnoediad to put his plots into action. Instead it was left to his three sons to turn the tide of the battle to Morgoth. This implies that Ulfang had died before the battle, though he may simply have been too old to take part.

Ulfang's name seems clearly interpretable as 'wolf fang' (or possibly some related form, such as 'seizing wolf'). These interpretations would make a linguistic connection between Ulfang's people and the Northmen who gave rise to the Rohirrim, though the two peoples were physically quite different. It seems unlikely that Tolkien intended a connection here (indeed at the time he named Ulfang, the Rohirrim would not be invented for some years). In volume V of The History of Middle-earth, it's said that this people spoke a quite alien language, so that it's possible that the simple interpretation 'wolf fang' is misleading, and this name has another meaning that remains unknown.