Earth-199999

Earth-199999 is an alternate universe defined primarily by the rise of Iron Man—and soon after, the Avengers—in the late 2000s and early 2010s, as well as the catastrophic Blip that caused half of all living things in the universe to disappear from 2018 to 2023. Following the Blip and the Avengers' Time Heist, various events caused the universe's timeline(s) and its separation from other universes to become unstable. The Time Variance Authority was dramatically restructured by a time-displaced variant of Loki and his allies, resulting in Loki himself becoming responsible for maintaining the endlessly branching timelines. Multiversal incursions caused by Doctor Strange and Spider-Man resulted in Spider-Man from Earth-96283 and Spider-Man from Earth-120703, as well as several of their respective enemies, to be briefly pulled from several different points in their timelines. Notably, this universe does not seem to operate on a sliding timescale like Earth-616 and other universes. Earth-199999 and its related universes are observed by a solitary Watcher, who lives in an interstitial multiversal space.

Earth-199999 has also been referred to as Earth-616, though this designation is of course already in use. In 2013, while committed to a mental hospital, Erik Selvig included the phrase "616 universe" on a chalkboard of what seemed to be pseudoscientific ramblings, but which also included his accurate assessment of the pending alignment of the Nine Realms. What he meant by the designation is unclear. Mysterio used the term in 2024 in an attempt to feign being a multiversal traveler, still lending the number no particular legitimacy whatsoever. However, when Doctor Strange legitimately traveled to Earth-838 in 2024, scientists there also observed his universe as number 616. Miguel O'Hara, a dramatically more knowledgeable figure on the multiverse than any previously mentioned, referred to this universe as Earth-199999. In any case, it appears that the universes with standard designations of 616 and 199999 exist in different multiverses, all but eliminating any chance of the two interacting.

Divergent universes

• Earth-21818: In 1988, the Ravagers accidentally pick up T'Challa while looking for Peter Quill. T'Challa's exceptional penchant for diplomacy has enormous implications when applied to galactic conflicts.
• Earth-29929: In 2015, Ultron successfully uploads his consciousness into a vibranium and Mind Stone powered body. He conquers the world and leaves it a desolate wasteland after a nuclear barrage. Thanos arrives on Earth seeking the Mind Stone to complete his Infinity Stone collection, but Ultron easily kills him and claims the Stones. The Infinity Stones make him virtually unstoppable, and he annihilates essentially all life in the universe. The resultant "peace" allows him to ascend to a higher consciousness and break through the multiversal barrier. The Watcher forms the Guardians of the Multiverse to combat the threat of "Infinity Ultron."
• Earth-32938: In 2008, while in the U.S. Navy, Killmonger rescues Tony Stark from the Ten Rings.
• Earth-51825: Nick Fury recruits Hope van Dyne to S.H.I.E.L.D. She is killed in action. Later, when Fury tries to assemble the Avengers in 2011, his candidates start turning up dead at the hands of Hope's vengeful father Hank Pym.
• Earth-72124: In ancient times, Odin leaves the young Loki on Jotunheim instead of adopting him. As a result, Thor is raised an only child, and becomes a much more irreverent, lighthearted version of himself.
• Earth-82111: In 1943, Peggy Carter takes the super-soldier serum instead of Steve Rogers, becoming Captain Carter.
• Earth-89521: In 2018, when Hank Pym tries to rescue Janet van Dyne from the Quantum Realm, he brings back a quantum virus, resulting in a global outbreak that turns almost everyone on Earth into zombies.
• Earth-91233: In 2016, Christine Palmer accompanies Doctor Strange in the car crash that injured his hands in Earth-199999: in this universe, she instead dies in the crash, and Strange causes cataclysmic damage to his soul and his world trying in vain to use the Time Stone to save her. He destroys the universe in the process, but escapes into the multiverse with help from the Watcher.

Uncatalogued

• In 2014, Ronan betrays and kills Thanos. As a result, Thanos's "daughter" Nebula flees, and soon joins the Nova Corps on Xandar.
• In 1988, the Ravagers return Peter Quill to Ego as instructed, and the young boy becomes a catastrophic force of Ego's will across the universe.
• Justin Hammer escapes from prison and attacks Avengers Tower on Christmas Eve hoping to steal Stark technology and the Hulk's blood. The tower's only line of defense is Happy Hogan.
• In 2012, after carrying the nuclear missile headed to New York through the Chitauri wormhole, Iron Man fails to return through the wormhole before it closes. Instead, he crash lands on Sakaar and has to find a way home amid the Grandmaster's deadly shenanigans.
• In ancient times, Surtur destroys Asgard. The Tesseract is sent flying to Earth, where it lands in a lake in precolonial America. The lake becomes a portal to another dimension. Over time, native Mohawk people go through the portal and are never seen again: in the other dimension, they gain special powers from the Tesseract. In the 15th century, a Mohawk girl named Kahhori goes through the portal while fleeing Spanish invaders, and must find a way to return home and fend them off.
• Following Odin and Hela's conquest of the Nine Realms, Odin strips the cocksure Hela of her power and banishes her to Earth, separating her from her crown and powers until she learns the value of mercy. There she meets Xu Wenwu and travels to Ta Lo, where she gains a new perspective on life.