In What if…? Episode 8, we see an alternate universe where the Avengers failed to steal the cradle from Ultron and, instead of Vision being born, Ultron was successfully able to upload his consciousness to the Android body, defeat most of the Avengers, and ultimately succeed in his plan to “pacify” Earth.

After Ultron is the ultimate force left on Earth, Thanos shows up with the Infinity Gauntlet bearing all the other Infinity Stones and this is where Ultron discovers that there are other stones than the Mind Stone, effortlessly kills Thanos and gets the stones for himself.

As far as I know, Ultron’s power should be similar to Vision’s now that he inhabits the same Android body that would become Vision in the main universe. This begs the question: why was he able to defeat Thanos so effortlessly when Vision seemed to be the Avenger most vulnerable to both Thanos and the Black Order in Infinity War?

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    Usually in the movies before a fight there is a dialogue between the two sides, and Thanos was expecting the same and was not ready to fight. During the episode I got the feeling that this version of Ultron is basically a living program which has just to accomplish his objective without losing time, so he just kills Thanos and grabs the gems. Rather than saying that Vision in the movies is weaker, I'd say that he is more human due to the fact that it contains Jarvis instead of Ultron, and so he has a moral/ethic which let him ponder on what is right and what is wrong, hence curbing his powers.
    – sound wave
    Commented Oct 1, 2021 at 5:04
  • @soundwave That sounds like the basis of a good answer (plus the injury Vis suffered without warning), why not write it up? Commented Oct 1, 2021 at 5:30
  • In Infinity War, Vision didn't try to fight Thanos and sought with Wanda and the other Avengers to destroy the Mind Stone. They were afraid of Thanos' powers and were desperate to avoid the activation of all the stones and the cataclysm that would result from it. On the other hand, Ultron thought of himself as godlike and wasn't afraid of the strange blue guy that just appeared in front of him.
    – Taladris
    Commented Oct 1, 2021 at 7:09
  • I wonder whether Vision in Infinity War could have sliced Thanos in two — it's possible that after he got hit by Corvus Glaive's blade, he wasn't capable of fighting back with full force. Commented Oct 1, 2021 at 11:28

4 Answers 4


It's simply the element of surprise.

The members of Thanos' Black Order, as well as the Mad Titan himself, have a tendency for melodrama. For example:

Ebony Maw: "Hear me, and rejoice. You are about to die at the hand of the children of Thanos. Be thankful that your meaningless lives are now contributed to…"

It's pretty natural that before a fight, both sides face off with a couple of iconic lines. Thanos would have been expecting as much.

Ultron, however, is not natural. He is completely logical (and fast) in his thinking, and know that there is no purpose in melodrama.

So he acted fast, and sliced Thanos into two perfectly balanced halves.

Why vision couldn't do it:

  1. Vision didn't want to take the Infinity Stones. Ultron did. The difference in motivation contributed to Ultron's decisiveness.

  2. Though Ultron and Vision share the same capabilities, their way of thinking is different. Ultron is entirely ruthless and efficient (a typical machine). Vision was somewhat aware of the concept of humanity, due to his previous job as Jarvis working with Stark. He was also worthy of lifting Thor's hammer (something I'm guessing Ultron couldn't have done), showing that he has Captain-America levels of morals and ethics. So Vision, due to his humanity, would first ponder on what is right and what is wrong, hence limiting the extent of his powers, as pointed out by @soundwave in the comments.

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    Plus Vision was never presented with the opportunity. In What If...?, Thanos appeared right before Ultron out of a portal, and Ultron immediately decided to kill him. In Infinity War, Vision was attacked by Glaive and Midnight, and only later heard about Thanos, second-hand, from Banner. Even attempting to fight Thanos at that point risked losing the Mind Stone; Vision had now way to know a Mind Stone beam could or would be an effective attack against this unknown enemy. Shame though — would have been much easier on Wanda and everyone else if Vision had made some Titan sashimi. Commented Oct 1, 2021 at 15:13

I think it is a combination of things.

Ultron is incredibly intelligent and homicidal. He is a psychopathic murdering machine that has no qualms nor regrets of killing someone. With how advanced the Vision body is, it would be no surprise that Ultron could compute in a picosecond the following:

(1) Those are other power stones (2) This purple giant has five of them, and is a threat (3) I need to kill him

During this time Thanos was probably about to say something, like introduce himself or demand the mind stone from Ultron.

Not only was Ultron faster on the draw, but Ultron would not hold back. He doesn't care about who or where Thanos came from, he just wanted to kill him.


I'm not sure if this is meant to be taken too literally. The scene you're referring to has a narrator talking over it, explaining a historical order of events leading up to the present time. I may be wrong, but it felt like just a summary to me.

As others have said, Ultron is very different than the Avengers. They were disunited and disorganized, unable to put together a coherent effort against Thanos. Ultron is different. There is definitely a lot to be said for the element of surprise as well. In many ways he was the perfect match for Thanos and probably defeated him with relative ease.

One last thing worth noting - Vision was severely weakened when Thanos confronted him in the mainline MCU. We don't really know how well Vision in his prime would have done against Thanos.


This show is about the multiverse. The director has said that there were multiple versions of the Thanos vs Ultron battle, but this is the only one shown. There were other universes where Thanos won; this is just the one fight shown in the series.

My source is bad (a Youtube short - https://www.youtube.com/shorts/cIO3feh5LBc), but it seems accurate.

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