| Bill Leith | |
| Position: | Pitcher |
| Birth Date: | 31 May 1873 |
| Birth Place: | Matteawan, New York |
| Death Place: | Beacon, New York |
| Bats: | Unknown |
| Throws: | Right |
| Debutleague: | MLB |
| Debutdate: | September 25 |
| Debutyear: | 1899 |
| Debutteam: | Washington Senators |
| Finalleague: | MLB |
| Finaldate: | September 25 |
| Finalyear: | 1899 |
| Finalteam: | Washington Senators |
| Statleague: | MLB |
| Stat1label: | Pitching record |
| Stat1value: | 0-0 |
| Stat2label: | Strikeouts |
| Stat2value: | 1 |
| Stat3label: | Earned run average |
| Stat3value: | 18.00 |
William Leith (May 31, 1873 – July 16, 1940), nicknamed "Shady Bill", was an American professional baseball player who played in one game for the Washington Senators during the season.