Thomas H. "Pat" Deasley (November 17, 1857 – April 1, 1943) was a 19th-century professional baseball player. Deasley primarily played catcher during his eight-year career from 1881 to 1888. Deasley played for the Boston Red Stockings, St. Louis Browns, New York Giants, and Washington Nationals over the course of his career. He died on April 1, 1943 in Philadelphia, Pennsylvania and is interred at the Mount Moriah Cemetery.