John Peter Thielman (May 20, 1879 – January 28, 1928) was a German-American pitcher in Major League Baseball who played from 1905 through 1908 for the St. Louis Cardinals (1905–1906), Cleveland Naps (1907–1908) and Boston Red Sox (1908). Listed at 5 ft 11 in (1.80 m), 175 pounds (79 kg), Thielman batted and threw right-handed. He was born in St. Cloud, Minnesota. His younger brother, Henry Thielman, also pitched in the majors. Thielman died at the age of 48 in Minneapolis, Minnesota.