A billionaire engineer who builds a powered suit of armour and, over roughly a decade, turns from the man who armed the world into the one who pays for it.
Tony Stark has no powers. This is the whole point of him. Everything he can do, he built, and everything he built he can be argued out of or blamed for.
He is the son of Howard Stark, an industrialist who helped shape the century and was never especially interested in being a father. Tony inherits the company at twenty-one and runs it the way a prodigy runs anything he was handed: extremely well, and without ever asking whether it should exist.
The armour changes what he can do. Being held in a cave by people using his own products changes what he wants, and the distance between those two things is the character. He spends the rest of his arc trying to make the world safe by building something, discovering that the something has made things worse, and building again.
Show detailsReading the character across the films
Stark is unusual in this material because his position reverses. He begins as the argument for individual power without oversight and ends as the loudest voice for accountability, and the films do not treat either position as obviously correct.
If you are watching for the first time, the useful thing to track is not the suits. It is who he is willing to be responsible for, and how that list grows.
Major spoiler
He dies. He uses the Infinity Stones himself in the final battle against Thanos, destroys him and his forces, and does not survive the injuries.