The fate of the Marvel Cinematic Universe's Celestials has been left ambiguous, but a film adaptation of the 2020 event comic King in Black could reveal what really happened to them. The Celestials are ancient beings with powers so immense they wielded the Infinity Stones in the past. In the MCU, they have been referenced most prominently in the Guardians of the Galaxy movies. In the first installment of the series, the titular team visited Knowhere, the severed head of a long-dead Celestial, in which a mining colony had been established. The race was thought to be extinct until Ego the Living Planet (Kurt Russell) appeared in Guardians of the Galaxy Vol. 2 with a plan to replace all life in the universe with extensions of himself. However, Ego remains the only living Celestial to show up in the MCU so far, and the circumstances of Knowhere and other Celestials' deaths are an enigma. What (or who) could have taken out such formidable beings remains one of the Marvel Cinematic Universe's greatest mysteries.

The King in Black event has prominently featured one of the Celestials' oldest enemies, Knull, as its central villain. Knull is an ancient evil god who lived in the Abyss, an endless cosmic void, prior to being awakened by the Celestials creating the universe. The appearance of light in his domain angered him, and Knull quickly came to hate the Celestials and their creations, and vowed to stamp them out to cloak the universe in darkness. In King in Black, Knull raised a symbiote army to take over Earth, and heroes and villains alike had to band together to resist the invasion.

Related: Marvel’s Eternals Theory: The Celestials Role In The Movie Has Been Revealed

Bringing Knull and King in Black's story to the Marvel Cinematic Universe would not only set the stage for a massive conflict that could top Avengers: Endgame, but would also clarify the Phase 2 mystery of what happened to the Celestials. A King In Black movie could include the horrifying reveal that Knull hunted down and killed them himself.

In the comics, Knull created the All-Black, a sword formed from his own shadow, after his awakening. To retaliate against the Celestials' light invading his territory, he used the All-Black to decapitate one in a single blow. He then used its severed head's powers as a forge to refine the sword before moving on. As the years passed, cities were established within the decaying head, and it earned the moniker of "Knowhere." This origin could easily be incorporated into the MCU.

Though millennia passed, Knull's hatred for the Celestials never faded, and his efforts to undo their work continued. He destroyed entire planets and civilizations, leaving only a void behind. On his path of conquest, Knull found that he could create symbiotes from darkness, which he could use to corrupt living things into monsters. Knull tracked down each Celestial and transformed them using the Living Abyss, which could be used in the MCU to explain their disappearance.

After the Infinity Saga, the Marvel Cinematic Universe needs a new big bad who can outdo the destruction wrought by Thanos without feeling too similar to the Mad Titan. Being a Celestial killer certainly makes Knull a good candidate in terms of sheer power, but it is his complete lack of civility and horror-influenced aesthetic that would really set him apart from Thanos. Knull's demonic appearance and disturbing methods of dispatching heroes are a far cry from Thanos' air of nobility and relatively "clean" plan to snap out life. With upcoming projects like Doctor Strange in the Multiverse of Madness and the Blade reboot bringing horror to the MCU, a King in Black movie could fit right in with them.

Next: The Origin of The Celestials In The MCU

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