Muhammad Ali, Jessie Owens, and Jackie Robinson are 100% heroes. These guys are civil rights giants and should be recorded in history as peers of Rosa Parks and Malcolm X. I can't think of anything more heroic than doing something to the best of your ability in the face of overwhelming adversity.
Stan Musial, Ted Williams, and my god Pat Tillman are heroes. These guys sacrificed years of their careers, one even lost his life defending an idea. Selflessness and sacrifice are heroic qualities.