John Leonard "Doc" Lavan (October 28, 1890 – May 29, 1952) was an American professional baseball shortstop who played in Major League Baseball (MLB) for the St. Louis Browns, Philadelphia Athletics, Washington Senators, and St. Louis Cardinals.

Lavan played in 1,163 major league games, of which 1,126 were at the shortstop position.

His range factor of 5.69 in 1916 was 0.77 points higher than the average shortstop that year.

In September 1917 (after Lavan committed 75 errors), Browns owner Phil Ball accused his players of lying down on the job.

He retired from military service after World War II as a Commander for the Naval Reserve.