| Billy Kelly | |
| Position: | Catcher |
| Birth Date: | 1 May 1886 |
| Birth Place: | Baltimore, Maryland, U.S. |
| Death Place: | Detroit, Michigan, U.S. |
| Bats: | Right |
| Throws: | Right |
| Debutleague: | MLB |
| Debutdate: | May 2 |
| Debutteam: | St. Louis Cardinals |
| Finalleague: | MLB |
| Finaldate: | October 5 |
| Finalteam: | Pittsburgh Pirates |
| Statleague: | MLB |
| Stat1label: | Batting average |
| Stat1value: | .290 |
| Stat2label: | Home runs |
| Stat2value: | 1 |
| Stat3label: | RBI |
| Stat3value: | 21 |
| Teams: | |
William Joseph Kelly (May 1, 1886 - June 3, 1940) was an American professional baseball player. He played in parts of four seasons in Major League Baseball for the St. Louis Cardinals and Pittsburgh Pirates from through . He also managed the minor league Port Huron Saints in 1922. Kelly was born in Baltimore, Maryland and died of lung cancer in Detroit, Michigan at the age of 54.
In a brief 4 year, 104 game major league career, Kelly compiled a .290 batting average with 32 runs, 1 home run and 21 RBI.