In Marvel's What If…?, Ultron used the Mind Stone to instantly bisect Thanos before the two could properly fight. In a fight without any Infinity Stones, however, Thanos would destroy Ultron, further cementing him as one of the MCU's deadliest threats.
Portrayed by Anthony Hopkins, Odin is the powerful ruler of the Nine Realms who has sworn to protect every kingdom under his rule. With Odin still ruling Asgard, Thanos would have easily been stopped had he made a play for the Infinity Gauntlet.
A machine can pick up the weapon and move it anywhere since it's mindless and incapable of possessing the morals necessary to be considered worthy. By this logic, Ultron himself could have lifted it, but it wouldn't have done him much good.
What If Director CONFIRMS Why Ultron Killed Thanos So Easily | Marvel Theory
Who can defeat Ultron easily?
Just as Thor or his Rune King version can easily defeat Ultron, Shazam (Billy Batson) shouldn't have any problem doing the same. Shazam's powers are magical and something Ultron might have difficulty processing.
While Thanos is an Eternal and has the standard powers of super-strength, agility, regeneration, immortality, and more, Adam Warlock takes the upper hand. He can be killed, but he resurrects to be stronger every time.
Thanos and Hulk have clashed several times in Marvel lore, with Thanos even admitting he was scared to face the Hulk before acquiring the Infinity Stones. While Thanos is usually the victor, it's generally down to him using superior tactics and technology, rather than simply possessing greater physical strength.
As it stands, Batman alone is helpless against cosmic level threats, much less against Thanos. Really, the best thing he could do is to ask for the Hellbat armor from the Justice League so he can survive Thanos' physical attacks. Even then, he'll still lose.
He simply wanted him dead at all costs because he was his biggest threat. As per the user, the director of Avengers confirmed that Thanos was most scared of Iron Man. “Not because of his strength, not because of his power, not because of his power, but because of his suit,” he added.
Lets answer this from a MCU point of view, since the comics isn't that consistent in their portrayal of characters while MCU is more or less consistent in their character development thus far. Thor is definitely stronger/more powerful than Ultron.
Who would win in an MCU fight: Odin or Thanos? Without the Infinity Gauntlet, Thanos stands little chance against Prime Odin. Odin is stated to be able to shatter the Earth.
The technology of Ultron is so powerful that two of the most dangerous Avengers can get insta-killed casually without either seeing it coming. Ultron defeated both She-Hulk and the Hulk not by outsmarting them or even besting them in a real one-on-one fight, but by overwhelming them both with his strength.
Ultron is one of the Avengers' greatest foes and his destructive rampages have been stopped by the team every time. Cap has been a part of those battles, but his part was mostly as the team leader. Anytime he tried to fight Ultron on his own, he was quickly dispatched by the android.
While the upgrades give Juggernaut the powers to kill Thanos with ease, it comes at the sacrifice of the former villain, as Juggernaut is abandoned after the Mad Titan is taken down, as no attempts are made to save him as he accelerates through space.
Exposure to so many enemies along with his trip through space may have weakened the Hulk to the point that he could bond with Bruce in Endgame, thus making the Professor persona appear much weaker. However, after snapping his fingers, the gamma burst should have raised his levels.
There's no question the Hulk is a near-indestructible force who comes out on top in almost all of his battles of pure strength. However, against Superman, he's outmatched. While Hulk's strength might rival that of the Man of Steel, Superman's other abilities give him a considerable edge against his opponent.
While Thanos has demonstrated a strong combat capability, dismantling Hulk in a series of rapid, well-aimed punches in Infinity War, taking into account Goku's Ki, transformations, and absolute refusal to give up until he's given it his all, Goku comes out on top.
By most accounts, Superman seemingly outclasses Thor in terms of raw strength, especially in earlier versions of the DC Universe. He's pulled planets, punched people into orbit, and performed all sorts of wild feats of strength.
However, Ultron's control over the Infinity Stones and the power he exhibited during his battle with The Watcher puts him on an entirely different level that could take out Galactus and his heralds.
Ultron sees the Avengers as one of the main problems with the world's stunted evolution. He particularly dislikes his maker Tony Stark and flies into a rage when compared to him. The evil A.I. has a particular dislike for Vision who inhabits the powerful body Ultron had built for himself.
Ultron's non-stop assessments for peace quickly led him to deem the entire human race as unstable and prone to self-destruction. He subsequently chose mass genocide as the solution to the error, with the Avengers being the obstacle standing in his way.
