Razorclaw the Butcher, having already been killed in the past, has a chance to be summoned as a ghost worgen by Baron Silverlaine when his health is brought to ~25%. He does not drop any loot nor does he say anything during the fight.
Razorclaw inhabited the former kitchen of Shadowfang Keep. He slaughtered many innocent humans in Shadowfang Keep when brought in by his master Arugal, hence his nickname.
Strategy
Razorclaw was easy, just having a tank keep aggro and then bringing him down. There was a patrol which walked around outside his room; to ensure you didn't end up fighting them with Razorclaw it was best to kill them first.