Let's consider the other side of the coin:

What is a hero?

I'll start it off by saying a hero is someone who goes out of their way to make someons elses life better.

I don't like any of Merriam Webster's definitions:

Main Entry: he·ro
Function: noun
Inflected Form(s): plural heroes
Etymology: Latin heros, from Greek hErOs
Date: 14th century
1 a : a mythological or legendary figure often of divine descent endowed with great strength or ability b : an illustrious warrior c : a man admired for his achievements and noble qualities d : one that shows great courage
2 a : the principal male character in a literary or dramatic work b : the central figure in an event, period, or movement
3 plural usually heros : SUBMARINE 2
4 : an object of extreme admiration and devotion : IDOL