One of the spookier rogues in the DC canon, Nekron is the Lord of the Land of the Unliving (or, you know, dead) and spends most of his days living (no pun intended) there, away from the plane of existence the DC heroes dwell in. He has full control over the dead who serve his every whim and whimsy. So deadly is Nekron that when taking on the full might of the Green Lantern Corps, they’re the underdogs.
Fortunately, as is usually the case with these big bads, Nekron has some very severe flaws in his game. One, he’s spent so much time in his dead land that he’s not accustomed to being in the land of the living and must bide his time for rifts between the worlds to open. Two, when the heroes bond with a being even more powerful than himself.
When Earth’s finest fuse with the seemingly all powerful Entity, they are able to resurrect Nekron’s trusted undead prophet, The Black Hand, damaging Nekron’s connection to the land of the living and allowing the heroes to finally terminate the DCU’s gnarly take on the Grim Reaper.