John Walker Lapp (September 10, 1884 – February 6, 1920) was an American professional baseball catcher.

He played in Major League Baseball (MLB) from 1908 through 1916 for the Philadelphia Athletics and Chicago White Sox.

In 1911, the Athletics' first-string catcher was Ira Thomas, with Paddy Livingston and Lapp backing him up.

Livingston, who had been a key figure during the regular season, was suffering from injuries to his legs, arms, and hands.

After battling influenza for several weeks, Lapp died on February 6, 1920, of pneumonia and is interred at Mount Peace Cemetery in Philadelphia, Pennsylvania.