Louis Harry Waidner (November 16, 1874 in Chicago, Illinois – August 11, 1944 in Evanston, Illinois[1]) was an American tennis player in the early 20th century.

In 1903, Waidner teamed with Kreigh Collins to reach the doubles final of the U.S. Nationals, losing to Reginald Doherty and Laurence Doherty, 7–5, 6–3, 6–3.

He lost the singles final to future International Tennis Hall of Famer Beals Wright, 7–5, 6–0, 6–3.

[2] A former president of the USTA/Midwest Section, Waidner has been enshrined in the USTA/Midwest Hall of Fame.

He also served as a member of the executive committee of the United States Tennis Association.