Duncan E. McKinlay (October 6, 1862 – December 30, 1914) was an American lawyer and politician who served three terms as a U.S. Representative from California from 1905 to 1911.

He later learned the trade of carriage painting and worked in Flint, Michigan, and San Francisco, Sacramento, and Santa Rosa, California.

After McKinlay's defeat, President William Howard Taft appointed him United States surveyor of customs for the port of San Francisco.

He died in Berkeley, California on December 30, 1914, and was interred in Sunset View Cemetery in nearby El Cerrito.

He concluded the speech calling for a renewal of the Geary Act which would "guard and protect [us] from the blighting curse of Asiatic immigration".