Harry Glenville "Doc" Tonkin (August 11, 1881 – May 30, 1959) was a Major League Baseball pitcher. Tonkin played in one game for the Washington Senators in 1907. He pitched in 2.2 innings, and gave up six hits and two earned runs. He also collected 2 hits in 2 at-bats with a run scored for a rare career 1.000 batting average. Tonkin was born in Concord, New Hampshire and died in Miami, Florida.