Anox Vi
These guys are kind of assholes.
Currently there are only two in the web. Penance on Triangle Island, and her brother Marathon, who has become the leader of the Republic of Man in Carrion. They are very long lived and very hard to kill, and generally even once you have killed one he or she merely returns to a place the call The Vast and awaits reincarnation.
An example of this is Marathon, who arrived on the doorstep of the royal palace at Tasset in the then Kingdom of Roan. He was adopted by Adelaide Bichass, who then proceeded to go a bit crackers as her son, then called Run rapidly aged so that within a few years he seemed outwardly to be of an age with her.
Penance once survived being devoured by Keaton Error's Zone Eater, which he threw at her in a last-ditch effort to save Maerius Chikara.