Justicar
Justicars demands JUSTICE!
On a more serious note, Justicars is a rank held by squad leaders that is unique to the Grey Knights Space Marine Chapter. The first rank above a Grey Knights Battle-Brother, a Justicar is the equivalent of the Space Marine Sergeant found in Codex Astartes-compliant Chapters. Holding this command is the first step on the path for a Grey Knight to become a Grand Master of the Chapter.
Justicars can also lead Grey Knights Terminator Squads, although such officers are usually referred to as a "Brother-Captain" rather than a Justicar. Unlike the lower ranks in the Grey Knights, a Justicar is permitted to wear his own personal heraldry as a sign of his position as a squad leader. Anval Thawn is a famous Justicar and a Mary Sue of questionable traits.
All Justicars are equipped with Aegis Terminator Armour (Optional), Wrist-Mounted Storm Bolter, Nemesis Force Weapon, Frag Grenades, Krak Grenades and Psyk-Out Grenades. Like all Grey Knights, Justicars are proficient at Hammerhand which is essentially Force Crush from Star Wars.