List of Grand Prix motorcycle racing World Riders' Champions

Grand Prix motorcycle racing is the premier championship of motorcycle road racing, which has been divided into three classes: MotoGP, Moto2, and Moto3. Former classes that have been discontinued include 350cc, 250cc, 125cc, 50cc/80cc, MotoE, and Sidecar. The Grand Prix Road-Racing World Championship was established in 1949 by the sport's governing body, the Fédération Internationale de Motocyclisme (FIM), and is the oldest motorsport world championship.

There were five classes when the championship started in 1949: 500cc, 350cc, 250cc, 125cc, and sidecar (600cc). The 50cc class was introduced in the 1962 season. Due to escalating costs that resulted in a number of manufacturers leaving the championship, the FIM limited the 50cc bikes to a single cylinder, the 125cc and 250cc bikes were limited to two cylinders and the 350cc and 500cc bikes were limited to four cylinders. The 350cc class was discontinued after 1982; two years later the 50cc class was replaced with an 80cc class, which was discontinued after 1989. In 2002, 990cc bikes replaced the 500cc bikes and the class was renamed as MotoGP. 600cc bikes replaced the 250cc bikes in the 2010 season, with the class re-branded as Moto2. In 2012, 250cc bikes replaced the 125cc bikes, with the class re-branded as Moto3, retiring the two-stroke bikes from Grand Prix motorcycle racing. MotoE was introduced in as a "world cup" until and thus statistics from that time span are not included here. MotoE gained world championship status from until , after which the class was placed on hiatus.

Giacomo Agostini, with 15 titles, is the rider with the most world championships across any class. Ángel Nieto is second with 13 world championships. Valentino Rossi, Marc Márquez, Mike Hailwood, and Carlo Ubbiali are tied for third with nine world championships each. Agostini also holds the records for the most victories in the 500cc/MotoGP and 350cc classes, with eight and seven world championships respectively. Phil Read and Max Biaggi have won the most 250cc/Moto2 championships, with four victories each. Nieto won the most championships in the 125cc and 50cc/80cc classes with seven and six victories respectively.