Alexander the Great is considered to be a very significant figure in Western Civilization because of the extent of the empire that he conquered and the lasting impact that his conquests had. However, it is going a bit far to call him a "superhero" given that that term is generally used to refer to people who have superhuman powers that they use for the good of their societies.
Alexander, of course, conquered an empire that stretched as far as what is now India. He and his descendants were not able to hold all of those conquests, but their actions did create a large Hellenistic civilization in the Middle East, stretching as far as what is now Iraq. The Hellenistic culture also had a great impact on the Romans, who saw Alexander and the Hellenistic culture as their role models. Because he conquered so much territory and because the Hellenistic society that arose from his conquests was so influential, Alexander is a major figure in Western Civilization.
However, calling him a super hero seems excessive. Even if we say that his leadership was superhuman, it is not as if he was selflessly working for the common good in the way that superheroes do. Instead, he was trying to gain more power for himself. This is not the act of a superhero.