| John Shaffer | |
| Position: | Pitcher |
| Birth Date: | February 18, 1864 |
| Birth Place: | Lock Haven, Pennsylvania, U.S. |
| Death Place: | Endicott, New York, U.S. |
| Bats: | Unknown |
| Throws: | Right |
| Debutleague: | MLB |
| Debutdate: | September 13 |
| Debutyear: | 1886 |
| Debutteam: | New York Metropolitans |
| Finalleague: | MLB |
| Finaldate: | June 30 |
| Finalyear: | 1887 |
| Finalteam: | New York Metropolitans |
| Statleague: | MLB |
| Stat1label: | Win–loss record |
| Stat1value: | 7-14 |
| Stat2label: | Earned run average |
| Stat2value: | 4.57 |
| Stat3label: | Strikeouts |
| Stat3value: | 58 |
| Stat4label: | Batting average |
| Stat4value: | .192 |
| Teams: | |
John W. Shaffer, nicknamed Cannon Ball, (February 18, 1864 – November 21, 1926) was an American baseball player. He played for the 1886 and 1887 New York Metropolitans. He continued to play in the minor leagues through 1897.