Thomas H. "Pat" Deasley (November 17, 1857 in Ireland – April 1, 1943 in Philadelphia, Pennsylvania) was a 19th-century professional baseball player. Deasley primarily played catcher for several teams during his 8-year career from 1881 to 1888. Deasley played for the Boston Red Caps, St. Louis Browns, New York Giants, and Washington Nationals over the course of his career.