| Bill Moriarty | |
| Position: | Shortstop |
| Bats: | Right |
| Throws: | Right |
| Birth Date: | August 1883 |
| Birth Place: | Chicago, Illinois |
| Death Place: | Elgin, Illinois |
| Debutleague: | MLB |
| Debutdate: | April 29 |
| Debutyear: | 1909 |
| Debutteam: | Cincinnati Reds |
| Finalleague: | MLB |
| Finaldate: | May 3 |
| Finalyear: | 1909 |
| Finalteam: | Cincinnati Reds |
| Statleague: | MLB |
| Stat1label: | Batting average |
| Stat1value: | .200 |
| Stat2label: | Home runs |
| Stat2value: | 0 |
| Stat3label: | RBI |
| Stat3value: | 1 |
| Teams: |
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William Joseph Moriarty (August 1883 – December 25, 1916) was a Major League Baseball player. He played shortstop in six games for the 1909 Cincinnati Reds. His brother, George Moriarty was also a professional baseball player.