10. Lennox Lewis
When he walked away from boxing in 2003, Lewis had nothing left to prove. He had become undisputed heavyweight champion of the world and beaten everyone he had ever fought as a pro – including the best of the new breed (Michael Grant and David Tua) and the best of his era (Mike Tyson and Evander Holyfield).
An Olympic gold medallist in 1988, Lewis launched himself into the world scene in the paid ranks when he battered Donovan ‘Razor’ Ruddock in 1992.
He went on to win the WBC, WBA and IBF heavyweight titles, and avenged brutal knockout losses he suffered to Oliver McCall and Hasim Rahman.
A 2002 hammering of Mike Tyson was the icing on the cake for Lewis, who had already proven himself and all-time great. He retired after beating Vitali Klitschko on cuts, behind on the scorecards at the time.
Lewis was brilliant and on his day, with his ability, dimensions and mental dexterity, he would have been a handful for any heavyweight in history.