| Gianni Leoni | |
| Nationality: | Italian |
| Gp Active Years: | 1949 - 1951 |
| Gp Teams: | Moto Guzzi, Mondial |
| Gp Race Starts: | 9 |
| Gp Race Wins: | 3 |
| Gp Podiums: | 8 |
| Gp Total Points: | 61 |
| Gp Poles: | 0 |
| Gp Fastest Laps: | 1 |
| Gp Last Win: | 1951 125cc Dutch TT |
| Gp Last Race: | 1951 250cc French Grand Prix |
Gianni Leoni (1 March 1915 - 15 August 1951) was an Italian Grand Prix motorcycle road racer from Como.[1] His best years were in 1950 when he finished second to Bruno Ruffo in the 125cc world championship and in the 1951 season, when he again finished in second place, this time to Carlo Ubbiali.[2] Leoni was the winner of the first Nations Grand Prix in the inaugural 1949 Grand Prix motorcycle racing season. He was killed while competing in the 1951 Ulster Grand Prix after colliding with his team-mate Sante Geminiani, who also died in this incident.[1]