"Superhero" is a relatively recent coinage. The ancient Greeks considered the mythological Herakles both a hero and a demigod, but didn't really have a word for "superhero".
Both DC and Marvel have a character named "Hercules." Both of them would probably qualify (the DC one was apparently at least somewhat villainous in his backstory, but had reformed by the time stories about him started).
Hercules
His father, Zeus, gave him powers.
Hercules
A "herculean" task (after Hercules' 12 labors).
Many superheroes have super strength but it is usually Superman. In mythology it is the great Hercules.
Zena is spelt Xena. The superhero Xena is a fictional TV program called Xena : Warrior Princess. Xena, once known as an outlaw is a healer and warrior, and teamed up with former enemy Hercules.
"SHAZAM" is an acronym representing the six mythical figures Solomon, Hercules, Atlas, Zeus, Achilles, and Mercury. These are the figures that grant the superhero Captain Marvel his powers in comic books.
is hawkeye a superhero
yes, he is a superhero
No, the word "superhero" does not have to be capitalized unless it is at the beginning of a sentence.
superhero
Yes, Spawn is a superhero.