Who is the greatest athlete in the world? It depends on your definition of the term.
Some people value winning and clutch performance over everything else and would consequently hand the title to a proven major sport champion like Tom Brady.
Others appreciate the blend of pure speed and strength, and might give their nod to a physical anomaly like LeBron James.
Still others might base their answer on a Darwinist equation of endurance and attrition, using their vote on someone like Lance Armstrong.
Or another sect could value individual success over team success, allowing a non-traditional athlete like Tiger Woods to take the crown.
But there is only one sport that actually has a system to determine the world's greatest athlete. Every couple of years—either at the Track & Field World Championships or the Summer Olympics—the winners of the men's decathlon (10 events) and women's heptathlon (seven events) are declared the world's greatest athletes by the track community.
And depending on how popular they are, maybe even briefly by the rest of the sports world.
Track might produce the planet's top athletes, but the sport's mainstream profile is lagging due in part to an inability to create sustainable superstars. As a helpful guide for the casual fan looking for a track athlete to latch onto, here are 30 of the biggest stars in track and field and their sports doppelgangers.