Carl Lewis is an American runner who had great success in sprinting events during the 1980s. He once won four gold medals at a single Olympic Games, in 100m, 200m, long jump and 4x100m relay in the Los Angeles games in 1984. He then managed to defend two of those titles four years later in Seoul. These and other achievements give him a claim to be one of the greatest Olympians, and indeed sportspeople, of all time.
In recent years, accusations and insinuations have been made that Lewis took performance-enhancing drugs. Certainly the era in which he competed was rife with doping, but nothing has ever been proven about Lewis and as such, his achievements stand and his greatness is untarnished.
Lewis's status as the best sprinter ever remained uncontested for two decades, although current competitor Usain Bolt arguably has a chance to overturn this depending on how much he goes on to achieve. Even if Bolt's running achievements do eventually eclipse Lewis's, he has yet to compete in the long jump, so Lewis would still be a more versatile athlete and his record of four track and field gold medals in one Olympic games is unlikely to be beaten.