Astorath
Astorath the Grim is the High Chaplain of the Blood Angels and one scary looking motherfucker.
Duties
As the Chapter's High Chaplain he holds the title of Redeemer of the Lost. This loosely translates into that if you're overcome by the Black Rage to the point where you can no longer serve in the Death Company Astorath comes along and chops your head off with his massive axe. Most Blood Angels do not feel comfortable around him for this reason: it is very well possible that they are the next to receive a viking crewcut from the Reedemer of the Lost. While some believe that Astorath causes the Blood Angels to succumb to the Black Rage this is far from the truth.
Astorath has a knack for sensing when the Black Rage is about to strike, and meets up with the brothers who are about to fall so he can lead them into glorious battle one last time. He makes no difference of Chapter in this, as Astorath's duties are beyond his own : he travels across the battlefields of all the Chapter's successors: so one month he can be fighting alongside the Flesh Tearers, and the next he is aiding the Lamenters. No matter the distance, Astaroth can feel the encroaching Black Rage in any of his battle brothers before even the brother himself starts feeling the effects.
Tabletop
On the battlefield Astorath soars into battle with his black-winged Jump Pack, wielding his axe like a madman to cleave and smite anyone who gets near him. His weapon, the Executioner's Axe, can cleave through armor and force fields alike and is more than a match for many a foe. And while he is 2+/4++ with 3 wounds, his two-handed axe means he swings at I1, so he's got a fair chance of being run through before he himself can deal any damage.
Trivia
Amusingly named as a pun on Astaroth, which itself is a derivation of "Astarte" who was a Deity of War in many of the ancient pre-Jewish religions of the middle east. Furthermore; Astaroth (and many other derivations) are often associated with various deities named "Baal" after whom the Blood Angels home planet is named.