The Terminator: Endgame is a three-issue comic series published by Dark Horse Comics in 1999. It concludes the events from The Terminator: The Enemy Within with a battle between the Machine, a new T-800 that has battled its way south from an appearance in the Canadian Tundra, and the last surviving Resistance fighter, Mary Randall, at the hospital where Sarah Connor is scheduled to give birth on October 4th, 1984.
Mary is aided in the battle by Detective Mark Sloan, who has come to believe in the existence of Skynet, Terminators, and the future war. Their battle is complicated by the interference of Sloan, who has been tracking a serial killer known as Catfish, who has also come to know of the future apocalypse and is seeking to insure it.
- The birth of Jane Connor on October 4th, 1984 causes the first documented spontaneous instant reset of events due to temporal interference. The last Terminator instantly vanishes, as do all effects and casualties of its presence, only deaths caused by human hands (Catfish) and Mary herself remain.
- Sarah maintains persistence of memory, as she initially asks for her son after Jane is born, still expecting the baby to be John. This represents a significant rift in continuity, or the space-time continuum. The fate of Kyle Reese is now uncertain.
- The Judgment Day still happens, but the Resistance under Janes's leadership completes the final assault on Skynet earlier, preventing it from initiating the predestination paradox cycle by never sending back the first terminator.
- Due to the persistence of Mary Randall in the past timeline after the reset, she still must undertake a temporal mission back to the past and meet Detective Mark Sloan for reasons as yet unspecified. Mary and Sloan still know each other, but do not know why they are where they are after the shift.
- Although the introduction of these characters in The Terminator: Tempest started by saying 1990 in the actual comics, they go back and retcon the situation because of the development of The Terminator: Endgame, centering around Sarah Connor's pregnancy and the birth of John Connor. In The Terminator: Endgame, they explicitly state several dates. The assassination on July 25 1984 happens two months and five days before Sloan records the casefile entry on Catfish on September 30, 1984. Other explicit dates are October 1st, 3rd, and 4th. Sara Connor is "forced" into the hospital in Odessa due to complications in her pregnancy because her baby is premature from the basis of the events of The Terminator happening in May of 1984. That is, unless you want Sarah to be pregnant for 6 years. The staff got it wrong for the initial Dark Horse stories of The Terminator: Tempest, The Terminator: Secondary Objectives, and The Terminator: The Enemy Within, and had to change it for the The Terminator: Endgame storyline.