The character first appeared in The Uncanny X-Men #191 (March 1985), and was created by writer Chris Claremont and artist John Romita Jr.[1] Hailing from the "Days of Future Past" timeline, Nimrod is a powerful, virtually indestructible descendant of the robotic mutant-hunting Sentinels.

The character was created by writer Chris Claremont and artist John Romita Jr., and first appeared in X-Men #191 (March 1985).

[4] Some time after this, Nimrod garners a reputation with the public of New York City as a heroic vigilante, assuming he is simply a man in powered armor.

[5] Nimrod later faces the combined forces of the X-Men and the Hellfire Club and proves himself as a powerful threat, killing Black Rook Friedrich Von Roehm, causing Harry Leland's fatal heart attack, nearly killing Nightcrawler and badly injuring Rogue and Sebastian Shaw.

The remains of both robots are pushed through the Siege Perilous, a mystical gateway that causes all who passed through it to be reborn with new bodies.

[9] In truth, between the time of Nimrod's first arrival and its apparent destruction when it merged with Master Mold and had traveled through the Siege Perilous, it had taken precautionary measures to ensure its survival.

It deactivates itself when Cable convinces Nimrod that its earlier creation in the timeline would cause a paradox and incalculable damage to the timestream.

Nimrod survives and travels back in time to March 1985, where the events involving Jaime Rodriguez and Kulan Gath's amulet play out exactly as they had originally with its memory corrupted, resulting in its existence in the 'true' timeline — with Rachel's history erased — becoming a temporal paradox.

[16] During a brief glimpse three months into the future seen in Uncanny Avengers, Havok, Scarlet Witch and Sunfire are shown fleeing from a new model of Sentinel.

[18] It was soon revealed that a human coalition of scientists and espionage agents from various secret agencies have joined forces to form Orchis, the ultimate mutant-fighting organization.

[19] Later on the Orchis Forge, it is discovered by Mystique during an infiltration mission that Director Killian Devo has completed work on an unknown component that Dr. Alia Gregor installs inside the torso of a Nimrod unit that is in the initial stages of construction.

Her mission coincides with Dr. Gregor preparing to resurrect her husband, Captain Erasmus Mendel, who was killed in the original Orchis raid, into the chassis of her newly constructed Sentinel prototype.

The activation succeeds and the crystalline memory transfer is successful, but the Erasmus persona prototype immediately detects the disguised Mystique as a Mutant and sacrifices itself to save the Orchis base by teleporting into space with the bomb she has triggered, leaving two emotionless duplicates without Erasmus' memory core yet uploaded to subdue Mystique before she can escape the station, and to protect Dr. Gregor.

Executing Mystique through the entrance of her Krakoa escape portal, the fearsome Sentinel announces his existence as "Nimrod, The Hunter" to the X-Men, who have failed once again in their attempt to destroy Orchis, vowing to hunt down and kill all Mutants.

[22] Having failed on all sixteen attempts to destroy the Orchis Forge, at the cost of numerous deaths and resurrections of nearly every X-Man involved in the attacks, Nimrod, who Dr. Alia Gregor laments is no longer carrying the Erasmus persona, has proven to be unstoppable.

[30][31] Similar to Nimrod, the Sentinels originate from a dystopian future and can alter their bodies to mimic and counter mutant abilities.