John Henry Ganzel (April 7, 1874 – January 14, 1959) was an American first baseman and manager in Major League Baseball.

Ganzel managed the Reds in 1908 and the Federal League's Brooklyn Tip-Tops in 1915.

His brother, Charlie, was a catcher who played with the St. Paul Saints, Philadelphia Phillies, Detroit Wolverines and Boston Beaneaters during 14 seasons, and his nephew Babe Ganzel was an outfielder for the Washington Senators.

In 1938 he headed the Orlando franchise of the Florida State League and was active with the club until his retirement in 1952.

Ganzel died at the age 84 of a sudden heart attack at a friend's house in Orlando, Florida on January 14, 1959.