| Jack Killilay | |
| Position: | Pitcher |
| Bats: | Right |
| Throws: | Right |
| Birth Date: | 24 May 1887 |
| Birth Place: | Leavenworth, Kansas |
| Death Place: | Tulsa, Oklahoma |
| Debutleague: | MLB |
| Debutdate: | May 13 |
| Debutyear: | 1911 |
| Debutteam: | Boston Red Sox |
| Finalleague: | MLB |
| Finaldate: | September 22 |
| Finalyear: | 1911 |
| Finalteam: | Boston Red Sox |
| Statleague: | MLB |
| Stat1label: | Win–loss record |
| Stat1value: | 4–2 |
| Stat2label: | Earned run average |
| Stat2value: | 3.54 |
| Stat3label: | Strikeouts |
| Stat3value: | 28 |
| Teams: |
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John William Killilay (May 24, 1887 – October 21, 1968) was a pitcher in Major League Baseball who played for the Boston Red Sox during the season. Listed at, 165 lb., Killilay batted and threw right-handed. He was born in Leavenworth, Kansas.
Killilay posted a 4-2 with 28 strikeouts and a 3.54 ERA in 14 appearances, including seven starts, one complete game, and 61 innings of work. Killilay died in Tulsa, Oklahoma at age 81.