John Victor Leathersich (born July 14, 1990) is an American former Major League Baseball (MLB) pitcher who played for the New York Mets, Chicago Cubs, and Pittsburgh Pirates between 2015 and 2017.

After graduating from Beverly High School, Leathersich attended the University of Massachusetts Lowell.

[4] Leathersich made his professional debut with the short season Brooklyn Cyclones of the New York–Penn League.

He was promoted to the High-A St. Lucie Mets after posting a 0.75 earned run average and 37 strikeouts in 24 innings.

[12] On July 30, 2015 it was announced Jack Leathersich would undergo season ending Tommy John surgery.

[13] Leathersich finished the 2015 season with a 0-1 record, 2.31 ERA in 17 games with 14 strikeouts in 11.2 innings pitched with a WHIP of 1.63 while giving up 12 hits, 3 runs, and 7 walks.