| Dennis Casey | |
| Position: | Outfielder |
| Birth Date: | 30 March 1858 |
| Birth Place: | Binghamton, New York, U.S. |
| Death Place: | Binghamton, New York, U.S. |
| Bats: | Left |
| Throws: | Right |
| Debutleague: | MLB |
| Debutdate: | August 18 |
| Debutyear: | 1884 |
| Debutteam: | Wilmington Quicksteps |
| Finalleague: | MLB |
| Finaldate: | July 24 |
| Finalyear: | 1885 |
| Finalteam: | Baltimore Orioles |
| Statleague: | MLB |
| Stat1label: | Batting average |
| Stat1value: | .273 |
| Stat2label: | On-base percentage |
| Stat2value: | .721 |
| Stat3label: | Slugging percentage |
| Stat3value: | .401 |
| Teams: |
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Dennis Patrick Casey (March 30, 1858 – January 19, 1909) was an American professional baseball player who played outfielder in the Major Leagues from -. He would play for the Wilmington Quicksteps and Baltimore Orioles. Dennis Patrick Casey is rumored to be the infamous "Casey at the Bat".