9. Ian Thorpe

High among the Thorpedo’s long list of achievements — Australia’s most successful Olympian, multiple world record holder, nice guy — is the fact that he is the only man to win a hat-trick of world championships in the 400 metres freestyle. In fact, he is the only man to win three consecutive titles in any of the sprint or middle-distance freestyle events (in the 1500 metres, of course, Grant Hackett has won four on the trot). What is often forgotten in his subsequent dominance is that Thorpe was quite literally a boy among men when he won his first world title as an unknown 15-year-old, way back in 1998 in Perth.