So, you may have seen that I have a new White Fang character called Niles Fenrir? Yeah, I know, edgy name, but it suits him. He's not a major villain like Adam or Cinder, he's more of a supporting villain, but that doesn't take away his brutality. He's also more mysterious as barely anyone knows what he looks like, but people know he exists due to the violent scenes he leaves behind. His reputation and unknown look has caused him to be given the nickname "Spøkelse" meaning ghost or phantom.
Unlike Adam who is more of a commander/soldier, Niles is an assassin who secretely yet violently kills important targets of the White Fang. In a way he's a bit like Tyrian, but less insane, and he's more of an arrogant sociopath than a cackling maniac. He doesn't exactly care for politics and isn't really a leader, simply enjoying killing his people's enemies and spreading his infamy, wanting to use his reputation of a remorseless killer to make the human elite bend to the White Fang's will. If Adam was the monster humans feared in the day, Niles would be the one they feared at night. Adam is the tip of the White Fang iceberg, Niles is the bottom of it. Adam is ruthless, but kills quickly, Niles likes to make his target suffer, to increase their fear of him and the White Fang. You get my point.
He's much less sympathetic than Adam, Ilia or Sienna, being more pure evil along the lines of Corsac and Fennec.
Weiss is so far the only human who has survived Niles, and now knows what he looks like.