Azrael is a codename used in DC Comics by the secret society, the Order of Saint Dumas (it itself a splinter group of the Knights Templar, popularised by the Assassin's Creed games). Named after Azrael, the angel of death. Two men have previously used the name, Jean-Paul Valley and Michael Lane, Lane is the current Azrael, Valley is deceased.
History (DC Comics)
Valley was genetically engineered for the role of Azrael by Order of Saint Dumas, but rejected it after being ordered to kill his father's killer, Carlton LeHah and became an ally of Batman. Valley temporarily became Batman when Bane broke Bruce Wayne's spine in the Knightfall story in the early 90s, but became corrupt and turned violent. After he recovered, Wayne defeated Valley and reclaimed the Batman mantle.
Becoming Azrael again, Valley attempted to redeem himself, teaming up with Batman on one occasion. But during a confrontation with an Azrael imposter, Carlton LeHah returned, shooting Valley, killing him. Valley briefly returned during the Blackest Night storyline, as one of the undead Black Lanterns, opposing not only all the different Lanterns such as the Green Lanterns, but all life itself.
A former police officer who became an attempt to create a successor to Batman gone wrong, Lane was chosen as the new Azrael by the Order. He wears the "Suit of Sorrows" and uses the "Sword of Sin." The suit is said to give its wearer enhanced strength, speed and stamina but at the cost of driving them insane.
Video Game Appearances
Micheal Lane appears in Batman: Arkham City as Azrael. He is the "mysterious figure" who is watching over Batman in the side mission "Watcher in the Wings." He introduces himself as Azrael and as part of the Order and provides an ominous prophecy to Batman before departing. In his biography it is stated that if Lane "does not keep his soul pure, the Suit of Sorrows will destroy him."