Athlete John Wesley "Jack" Glasscock (July 22, 1859 - February 24, 1947) was one of 19th-century baseball's premier shortstops. Born in Wheeling, Glasscock was called "Pebbly Jack" because of his habit of "grounds keeping" at his position, picking up and tossing away pebbles, which some baseball historians claim were imaginary.

Glasscock, who played bare-handed, was one of the first to use a signal to inform his catcher which middle infielder would cover second on a steal and was one of the first shortstops to back up throws to the second baseman. Glasscock played in 1,736 games and had a batting average of .290 with 27 home runs and 752 RBIs. For five times in his career, he topped the .300 mark in his batting average.

Glasscock's debut occurred May 1, 1879, playing for the Cleveland Blues. In addition to Cleveland, he played for several other teams, including the Cincinnati Reds, the Indianapolis Hoosiers, the St. Louis Browns, and the New York Giants. While managing Indianapolis for part of 1889, Glasscock led the National League with 205 hits. In 1890, while playing with the Giants, he won the National League batting title, hitting .336.

In 1895, Glasscock returned to his hometown of Wheeling to manage and play first base for the Wheeling Base Ball Club. He died in Wheeling.