Valentino Rossi is considered one of the greatest motorcycle racers of all time. He started racing go-karts as a child and began his professional career in 1996 in 125cc Grand Prix, winning his first world championship the following year. Rossi went on to win multiple world championships across several categories, including 250cc, 500cc, and MotoGP with Honda and Yamaha, making him the rider with the most wins in the premier class.