Daniel Maurice Casey (November 20, 1862 – February 8, 1943) was an American professional baseball player whose career spanned from 1884 to 1894 and 1899.

Casey led the National League with a 2.86 earned run average (ERA) and four shutouts in 1887 while playing for Philadelphia.

The poem's author denied that his work was based on any real player, and several sources have called Casey's claim into doubt.

Casey grew up with five siblings on the family's farm in Broome County, New York, a short distance from Binghamton.

[3] Casey continued to play for the Quicksteps after the team joined the Union Association in August 1884, compiling a 1–1 record and 1.00 ERA in two games.

He began the season with the Indianapolis Hoosiers of the newly formed Western League and compiled a 10–2 win–loss record and a 0.50 ERA in 12 games.

He asserted that he had hit a "lucky" home run against Boston a week earlier and that Philadelphia trailed, 4–3, when he came to bat and struck out.

[10] Casey claimed the area drew the name "Mudville" because the site was a vast mudhole before the ballpark was built.

"[6] Two months later, in May 1938, Time magazine published a story referring to Casey as the "Mudville Man.

But despite this evidence, original 'Caseys' continue to appear, including Daniel, who was the most persistent and told the story so often he unquestionably came to believe it.

"[15] Another writer examining the claim concluded that the game cited by Casey as the inspiration for Thayer did not end in a 4–3 defeat of Philadelphia.

Rather, Casey got a hit in the ninth inning, driving in two runs, and the game was called due to darkness in a 5–5 tie.

That he didn't get it is evidence that Thayer was not writing about any incident in 1887 and that the late Dan Casey either was shortchanged, or was not the hero the author had in mind.