Like his fellow Horsemen, Death is of a race known as Nephilim – among the most powerful beings in the Universe. When Mankind was given the prize of Eden, Absalom – leader of the Nephilim – led his armies against Heaven and Hell in an attempt to steal it back. For this crime, the Charred Council condemned the Nephilim to destruction. The Four Horsemen of the Apocalypse were granted a reprieve from this fate on the condition they aid the Council’s victory over their kin. The Horsemen accepted, but it was Death who bore the greatest burden of guilt for the near extinction of his race. Donning his iconic mask to represent his role as executioner on the day he slaughtered his brethren, he has not removed it since.
The Owl Sector is a civilian scientific organization that advises and assists the Vanguard, with its headquarters located in an observatory at the highest point of the Tower. Its members consist of citizens of the Last City who desire to support the Guardians. The Owl Sector's focus appears to be analyzing and discovering the purpose of unexplained Golden Age technologies.