How Did Thanos Really Die In Doctor Strange 2 - And Who Killed Him?
In "Doctor Strange in the Multiverse of Madness," a variant of Stephen Strange (Benedict Cumberbatch) is responsible for the death of Thanos (Josh Brolin) in his universe. However, unlike the Earth-199999 version of the hero who helped find a 1/14,000,065 solution to defeating the Mad Titan using the Time Stone, Earth-838's Illuminati ended up killing the villain by turning his own weapon against him.
In the Sam Raimi-directed sequel to "Doctor Strange," part of the film deals with Doctor Strange and America Chavez (Xochitl Gomez) being captured by Earth-838's Illuminati. America and Stephen are then told the truth about what happened to the Illuminati's version of Stephen Strange and Thanos.
Unlike the main Mad Titan, who successfully snapped half of all life from existence with the Infinity Stones after defeating heroes on the planet Titan, Thanos was brutally killed in the alternate reality. At the same time, the Illuminati were also forced to take out one of their own after he became corrupted by the Darkhold. While the Illuminati successfully eliminated Thanos, as he can be seen in the flashback impaled by his sword — it came at a significant cost.
The Illuminati's Doctor Strange was out of control
In the film, Thanos and Doctor Strange's death is directly tied to the Illuminati on Earth-838, with the hero being joined by a powerful group including Captain Carter (Hayley Atwell), Captain Marvel (Lashana Lynch), Mister Fantastic (John Krasinski), Professor X (Patrick Stewart), and Black Bolt (Anson Mount). Charles Xavier explains that the team used the Book of Vishanti against Thanos and reveals via telepathy what happened in the alternate reality's battle on Titan.
While the final fight between the Illuminati and Thanos isn't shown, viewers see the villain lying dead with the Infinity Gauntlet on his hand and his iconic blade sticking out of his lifeless corpse. There's no question that defeating the Mad Titan must have been the ultimate task for the team. There's no reason to believe he wasn't as powerful as his Earth-616 counterpart.
Despite their efforts, the universe-saving mission ends not only with another entire universe dying due to Strange's actions but the former hero's demise as well. Doctor Strange's corruption by the Darkhold while trying to stop Thanos led to an incursion that wiped out an entire universe. The Illuminati saw the mystical hero's methods stand against everything they stood for as a collective, leading to the hero being executed by Black Bolt's sonic scream. So, while the Illuminati killed Thanos by seemingly turning his own weapon against them, it came at a profound loss of life.