Michael Joyce O'Neill (5 October 1877 – 12 August 1959) was a starting pitcher and left fielder in Major League Baseball.

He was born in the village of Maum, in County Galway, Ireland, to Michael O'Neill, a landholder, and Mary Joyce.

O'Neill responded by hitting the first pinch grand slam in major league history off Togie Pittinger of the Boston Beaneaters.

[2][3] It was an inside-the-park home run as O'Neill became the first National League pitcher to hit a grand slam in the 20th century.

He also played with the Cincinnati Reds in 1907, strictly as a reserve left fielder and pinch-hitter, retiring from baseball at the end of the season.