What makes a hero? The definitions in Merriam-Webster and the Oxford dictionaries go first and second to Greek classicism and the third definition gets to the heart of it.  

c : a person admired for achievements and noble qualities

Our world has too few real heroes who act with nobility. Martin Luther King, Jr. was a hero and his friend and colleague, Georgia Representative John Lewis, acts with same kind of integrity and purpose to try to do the right thing.