| John Greason | |
| Position: | Pitcher |
| Bats: | Unknown |
| Throws: | Unknown |
| Birth Date: | 1851 7, mf=yes |
| Birth Place: | Washington, D.C. |
| Death Place: | Washington, D.C. |
| Debutleague: | MLB |
| Debutdate: | August 27 |
| Debutyear: | 1873 |
| Debutteam: | Washington Blue Legs |
| Finalleague: | MLB |
| Finaldate: | September 6 |
| Finalyear: | 1873 |
| Finalteam: | Washington Blue Legs |
| Statleague: | MLB |
| Stat1label: | Win–loss record |
| Stat1value: | 1–6 |
| Stat2label: | Games pitched |
| Stat2value: | 7 |
| Stat3label: | Earned run average |
| Stat3value: | 5.86 |
| Teams: | |
John A. Greason (July 29, 1851 – July 22, 1889) was an American professional baseball player from Washington, D.C. who pitched a total of seven games for the Washington Blue Legs of the National Association of Professional Base Ball Players.[1] In his short one-season career, he started and completed all seven of his games, had a 1–6 win–loss record and a 5.86 ERA.[1]