Warning: The following contains spoilers for What If...? Season 1, Episode 8 "What If... Ultron Won?" Streaming now on Disney+.

What If...? is an imaginative journey that looks through and explores the endless possibilities of the multiverse, in creative ways. The last two episodes of the first season focus on what would have happened if Ultron found and inhabited the vessel and body instead of Vision, thus gaining control of the Mind Stone.

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The events that transpire see Ultron surpass Thanos in terms of threat level, especially due to his goal being complete eradication of humanity in the name of peace, compared to Thanos's half and half ideals. It turns out that the Infinity Stones in the possession of a rampant AI hellbent on the destruction of worlds and universes is worse than any threat previously faced.

9 Ultron In Possession Of The Mind Stone Immediately Dispatched Of The Avengers

Tony Star in What If... Ultron Won?

In this alternate timeline where Ultron gains control of the Mind Stone, his unstoppable wrath and power begin by eliminating the main bulk of the Avengers, with Hulk, Thor, and Iron Man in particular being shown falling to the AI's newfound power.

A previous shot shows more members in the room, with it being implied that every Avengers member as of Age of Ultron, was wiped out in one go. Ultron was a tough enough villain and adversary for the Avengers anyway, but the Mind Stone turned him into an unstoppable force.

8 After The Demise Of The Avengers, Ultron Was Free To Utilize The Mind Stone And Release All Of Earth's Nukes

Ultron Vision kills Thanos in episode 8 of What If

Simultaneously with the destruction of the Avengers in this particular timeline, Ultron coordinated the launching of Earth's entire arsenal of nuclear weapons, tearing the world apart with utter destruction.

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This was all with but one Infinity Stone in his possession. Immediately wiping out the Avengers left no hope in stopping the nuclear destruction of Earth, and the fact that there was no Vision to foil Ultron in this universe, was simply the nail in the coffin for the fate of Earth and humanity.

7 Ultron Easily Eliminated Thanos In Brutal Fashion

Thanos killed in What If?

As Ultron watches on and admires the decimation of Earth, Thanos turns up in search of the Mind Stone, the last Stone he needs to complete the Infinity Gauntlet. Incredibly, Ultron simply kills him immediately using his newfound destructive strength, before Thanos even has time to activate any of his own powers to prevent or alter what was happening.

Thanos effectively brought the Infinity Gauntlet with most of the work already done, directly to an already powerful AI, given Ultron the complete set and a new level of power. While this version of Thanos will not garner sympathy from viewers like the Ravager version shown previously in the series did, his immediate annihilation was shocking, in certainly a ruthless and cruel move from Ultron.

6 Ultron's Use And Abuse Of The Reality Stone Spawned A Seemingly Endless Supply Of Sentries

Nat and Clint What If

With Ultron possessing the full set of Infinity Stones, he utilizes the Reality Stone to form a huge army of Sentries to operate in all of the reaches of the universe, for even with all of his power, he still can't be everywhere at once.

These Sentries almost quell humanity's last hope, Natasha Romanoff and Clint Barton, the only known survivors of the nuclear holocaust, who are working in an almost post-apocalyptic version of Earth, as they journey to the KGB headquarters to find intel on beating Ultron. The sheer volume of Sentries causes Clint to take it upon himself to make the ultimate sacrifice in taking several of them out and allowing Natasha to escape with humanity's hope. Ultron's army of Sentries assisted Ultron in committing many atrocities and also enacted more in his absence.

5 Ultron Annihilated Every Planet Within His Universe

Ultron in What If... Ultron Won?

What ensues is Ultron ruthlessly running through and destroying planets with seamless effort. Starting with Asgard and subsequently moving to the Sovereign, Sakaar, and Ego, the rest of this timeline's planets and remaining heroes, including the Guardians of the Galaxy, are systematically annihilated and eliminated.

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Ultron and his utilization of the Stones make everything that Thanos achieved in the initial timeline seem almost trivial and irrelevant in comparison, with Ultron edging closer to his goal of peace from total universal destruction.

4 Even Captain Marvel's Best Efforts Were Immediately Undone By The Power Of The Stones

What If Captain Marvel fights Ultron

Ultron faces his first real test of his universal conquest when he encounters Carol Danvers, Captain Marvel, during his invasion and annihilation of Xandar. Danvers immediately drives Ultron down towards the planetary core, with the aim of destroying Ultron entirely.

However, possession of the fully equipped Infinity Gauntlet is often seen to allow the user to cheat death if they wish it, and Ultron is able to undo all of Captain Marvel's hard work and wipe her out in one move, subsequently destroying Xandar and finishing his universal conquest.

3 Ultron's Hunger For Conquest Led To Him Noticing The Watcher And Infiltrating The Realms Of The Multiverse

Infinity Ultron defeating the Watcher in What If...?

Ultron's quick rise to power and subsequent annihilation of life within this universe quickly turns from a brief moment of peace to dissatisfaction of having nothing left to conquer. While Uatu, the Watcher, continues to narrate, Ultron's heightened power with the absence of other beings, allows him to sense the Watcher.

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With him instantly realizing that this means there are more universes to conquer, Ultron's hunger for ultimate power is once again reignited and he hunts the Watcher, searching for a way to break through to the multiverse. He eventually manages to breakthrough, leading to a fight with the Watcher, which sees them journey through multiple universes and timelines.

2 Ultron Made The Watcher Question Himself And Resort To Breaking His Oath

Watcher and Strange Supreme What If Episode 8

While the Watcher can barely hold his own against the supreme power of Ultron, Ultron tries to hurt him mentally by casting blame on the Watcher, "All those worlds, all that suffering and you just watched".

The Watcher was simply doing his job, obeying and abiding by his oath in not interfering, but Ultron managed to get through, casting doubt and guilt upon him, in an act of cruelty not purely made of physical destruction for once. The Watcher eventually has to retreat and he escapes to Doctor Strange Supreme's prison, joining forces with him and breaking his oath. This leads to him rounding up the heroes from the previous episodes of What...If?, readying them for the final stand against Ultron.

1 Ultron Reached Unfathomable Heights And Power Surpassing The Watcher

Watcher and Ultron

Ultron's new position and obsession with the multiverse grew in the absence of the Watcher in his post, meaning that his power had elevated him to a position where he was essentially the Watcher himself. It was the culmination of all of his efforts in universal and multiversal dominance, annihilating almost everybody that had ever opposed him.

This newfound power of observation is ultimately used against him in episode 9, to lure him towards the Guardians of the Multiverse, with Thor getting his attention with an extraordinary amount of thunder. However, it was still an immensely cruel application of power, to be able to watch everything and impact it at his will.

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