| William Pierson | |
| Position: | Pitcher |
| Bats: | Left |
| Throws: | Left |
| Birth Date: | 14 June 1899 |
| Birth Place: | Atlantic City, New Jersey |
| Death Place: | Atlantic City, New Jersey |
| Debutleague: | MLB |
| Debutdate: | July 4 |
| Debutteam: | Philadelphia Athletics |
| Finalleague: | MLB |
| Finaldate: | May 2 |
| Finalteam: | Philadelphia Athletics |
| Statleague: | MLB |
| Stat1label: | Win–loss record |
| Stat1value: | 0-1 |
| Stat2label: | Earned run average |
| Stat2value: | 3.38 |
| Stat3label: | Strikeouts |
| Stat3value: | 10 |
| Teams: | |
William Morris Pierson (June 14, 1899 – February 20, 1959) was a Major League Baseball pitcher who played from to, and again in with the Philadelphia Athletics. He batted and threw left-handed.