The pair went head to head in Avengers: Infinity War and Avengers: Endgame, but it has been pretty clear from all the way back in the first Avengers movie that Thanos was the Stark's embodiment of fear.
Because of his understanding of time travel, the theory states, Kang is fearful that Iron Man could take him down. It is possible that He Who Remains set up the flow of time in a way that Tony Stark died while fighting Thanos, giving Kang the opportunity time to invade.
However, Kang eventually decided to chance a meeting with Thanos, despite his policy, near the end of The Infinity Siblings storyline, though it was still a choice founded by his fear of the Mad Titan.
the Avenger Thanos is most scared of is Tony Stark. Not because of his strength, not because of his powers, not because of his suit, but because his intelligence. That is why Thanos says. you're not the only one cursed with knowledge.
However, while Tony did make amends with Steve, he wasn't able to do so with Bucky. In fact, they didn't even get to have any interaction before Iron Man's death.
Rhodey is Tony's best friend and an officer of the US military. He often argues with Tony. He even stated that Iron Man can't do this alone, but Tony never listens. Despite their personality clashes, the two do care for each other.
James Rhodes is a fictional character originally portrayed by Terrence Howard and subsequently by Don Cheadle in the Marvel Cinematic Universe (MCU) media franchise, based on the Marvel Comics character of the same name. He is initially depicted as a U.S. Air Force officer who is the best friend of Tony Stark.
Summary. Thanos considered Iron Man a significant threat, as he prepared to use four Infinity Stones to kill him during their battle on Titan in Avengers: Infinity War. Iron Man's past actions, such as single-handedly defeating Thanos' forces in The Avengers, earned him the fear and respect of the Mad Titan.
Two things. Alcohol and arrogance. These two things are his biggest weaknesses. You could make an argument about his suits durability, his weakness when he doesn't have suits (to which I simply say, Bleeding Edge), etc.
5 His Heart. Tony Stark's heart is electronically powered and can run out of battery if he uses too much power in his suits. This is one of his main weaknesses because the heart can give out during the course of a highly intense battle.
Thor was also worried about Ultron's threat after perceiving Tony Stark's work with the Mind Stone as a betrayal. He fears a loved one and an ally turning on him mainly because Thor doesn't like to consider the possibility that a person he trusts can hurt him in a way that he would never do to them.
Because of the Hulk's incredible strength which seemingly has no limit, Thanos was afraid to fight him without the help of the Infinity Stones. While Thanos had been afraid to fight the Hulk as revealed in The Thanos Quest, it didn't seem like he needed to be, as proven in that very same comic.
Thor. Thanos, killed his best friend, killed his brother, and snapped a lot of his friends (Avengers). He can't even here his name. So yes, it should be Thor.
Along with always contently competing to be the best, these two could never really get along because of their big egos. Steve truly believed his way of thinking was right, while Tony could only see his side of things.
Tony's PTSD symptoms include nightmares, flashbacks, anxiety attacks, invasive and violent memories, but he is successful at managing his symptoms when he is away from his suits.
Marvel has confirmed Reed Richards is actually smarter than Tony Stark in a hilarious way, as the Fantastic Four hero became dumber after Iron Man shared his intellect with every living person in his city.
While Kang and his evil variants could benefit from ruining or interrupting Thanos' plan, they would risk their own existence without the stability that the Sacred Timeline provides.
The Avengers bring a young Thanos (before he's become aware of the Avengers' existence as his future adversaries) to fight Kang. The two battle it out, but Kang grabs Thanos by the neck and forces time through his body, aging him an eternity in a matter of seconds and leaving only a skeleton behind.
So while Thanos may be the more intimidating villain right now, the sheer multiversal scale of the threat posed by Kang makes him a likely candidate for the most powerful villain in the MCU.
