Angels of Vengeance
The Angels of Vengeance are a successor Chapter of the Dark Angels, divided from their parent legion during the Second Founding.
In a strange break from the established tradition of the "parent" chapter keeping all of the iconography and the successors making up their own, the Angels of Vengeance got to keep the original black colour scheme whilst the parents painted themselves green and only kept the family logo.
In temperament, the Angels of Vengeance make the Dark Angels look like respectable party organisers. They generally ignore everyone and everything else and get shit done. More-so than other space marines, the Angels of Vengeance simply do not understand the concept of failure and will stubbornly pursue their own objectives even if it obliterates themselves. Unfortunately this has a caused many problems where their own military objectives conflict with anyone else's, giving them a bad reputation as the sort of dudes who win a battle only to cost themselves the war.
Despite this, they have an honour roll as long as any other second founding chapter, which is pretty much the only thing that stops other chapters from looking down on them as retards.
Of course the level of disdain the Angels of Vengeance holds for others obviously does not extend to other members of the Unforgiven, since they share an overall command structure with the Inner Circle and they have similar formations to the Deathwing & Ravenwing. In fact during a period where three masters of the Ravenwing died in quick succession and the Dark Angels were yet to figure out why, the Angels of Vengeance subbed in their own 2nd Captain to fill the vacancy.