The Honourable Louis Orville Breithaupt (October 28, 1890 - December 12, 1960), served as the 18th Lieutenant Governor of Ontario from 1952 to 1957.

Born in Berlin (later Kitchener), Ontario, he was educated at the University of Toronto. He rose to become head of his family's leather business, Breithaupt Leather Company, in Kitchener. He was a Kitchener alderman for four years and in 1923 became the youngest mayor in the city's history. He was a Liberal Member of Parliament from 1940 to 1952.

Breithaupt was appointed Lieutenant Governor of Ontario in 1952 and served until 1957.

He was active in many service groups, such as the YMCA and Rotary Club. He became Chancellor of Victoria University in 1959, and died in Toronto in 1960.

In 1953 he was awarded an honourary LL.D. from McMaster University.

Preceded by: Ray Lawson

List of Lieutenant Governors of Ontario

Succeeded by: John Keiller MacKay

Preceded by: William Daum Euler , Liberal

Member of Parliament from Waterloo North (1940-1952)

Succeeded by: Norman Schneider , Liberal