Jacob Weimer, nicknamed "Tornado Jake" (November 29, 1873 – June 19, 1928), was an American professional baseball player. He played in Major League Baseball as a left-handed pitcher for the Chicago Cubs (1903–1905), Cincinnati Reds (1906–1908) and New York Giants (1909). He batted right-handed and threw left-handed. Weimer was born in Ottumwa, Iowa. He toiled for eight years in the minor leagues, before becoming one of the top left-handers in baseball. He was also a good hitting pitcher in the majors, posting a .213 batting average (115-for-540) with 46 runs, one home run and 36 RBI.