What defines a hero?

My assignment:  Think about people who deserve status as heroes? From the past, from the present, from life, and from literature. What defines a hero? Write a five-paragraph essay that develops your definition of heroism. Be sure to use strategies of definition (function, example, and negation) to guide your writing.
The essay is to be TYPED, 12PT FONT, TIMES NEW ROMAN, DOUBLE-SPACED, with a TITLE, and a HEADING!