Nekron is a supervillain appearing in comic books published by DC Comics, primarily as an enemy of the Green Lantern Corps. Created by Mike W. Barr, Len Wein and Joe Staton, the character, who exists as an embodiment of Death, first appeared in Tales of the Green Lantern Corps #2 (June 1981). He is the primary antagonist in the 2009–2010 Blackest Night storyline.

Nekron is the personification of Death and ruler of a region adjoining Hell known as the Land of the Unliving. It is where the souls of the dead await passage to their final residence in either the Silver City or Hell. Nekron draws his power from the souls and spirits of the dead.

After the Oan scientist Krona is sentenced to banishment as pure energy, his energy reaches Nekron's realm, opening a rift between dimensions. Desiring the living world he is now able to see, but being too large to pass through the rift, Nekron recreates Krona as an undead being of enormous power instead. Given an army of similarly-restored spirits, Nekron sends Krona to kill the Guardians of the Universe to increase the size of the rift. Krona cooperates because part of Nekron's plan involves collapsing the universe so as to recreate it according to his own desires. Krona and his minions kill several Guardians and Green Lanterns while destroying the Central Power Battery to prevent the Lanterns from recharging their power rings. Although his attack is powerful enough to shatter the morale of the Green Lantern Corps, Hal Jordan manages to inspire and rally his fellow Lanterns into attacking Krona with the charge still left in their rings. Nekron is defeated when Jordan enters the realm of the dead and incites the spirits of the recently killed Lanterns to rebel against him. This distraction undercuts Krona's power supplied by the being and thus gives the Guardians enough time to banish Krona into the dead realm and close the rift with Jordan still trapped inside. The spirit of Jordan's predecessor, Abin Sur, helps him escape the realm.

Captain Atom has a run-in with Nekron in which Nekron is described as "Death as the Ultimate Opponent". Black Racer, also making an appearance, is coined "Death as an Inevitability", while Death represents "Death as the Release, as Mercy, as Compassion". Drawing into the Quantum field, Captain Atom is able to get the better of Nekron and is able to visit his deceased wife.

Nekron later battles the demon Nebiros, following the destruction of Doctor Fate's Tower of Fate. Also appearing in this issue is Jared Stevens (Fate).

Kyle Rayner later encounters Nekron when he nearly reenters the living universe, at a time when the level of supernatural activity mysteriously increases. This gives Nekron the opportunity to briefly control every deceased member of the Green Lantern Corps, which act as both his army and his anchor to the living universe. Kyle pushes Nekron back into his dimension by freeing the undead Lanterns from Nekron's control. The rift is sealed following Nekron's defeat.

In the Blackest Night storyline, Nekron is revealed to be responsible for the creation of the black power rings, which reanimate the dead, and is collaborating with Scar and Black Hand. He is also responsible for the capture of the Anti-Monitor during the aftermath of the Sinestro Corps War on the planet Ryut. When the Black Lanterns' power levels reach one hundred percent, Nekron is summoned just outside Coast City. Nekron is also revealed to be the mastermind behind the miraculous resurrections of several superheroes in the past, a deed previously thought to be a consequence of Brother Blood tampering with the forces of life and death.

According to Black Lantern Jean Loring, Nekron was formed out of the nothingness in existence prior to the creation of the universe as a defense mechanism to the Life Entity, also known as the White Light. Given shape in the form of life's idea of death, Nekron marches with his undead army, claiming the hunger plaguing him has not abated. Nekron is not a living being, instead existing as an avatar of darkness.