Henry Key Milner (born September 25, 1866 in Greenville, Butler County; died December 26, 1939) was a civil engineer for the Birmingham Water Works, a mine supplier, a real-estate developer, and a founder of the Birmingham Country Club.
Milner was the son of engineer Willis Julian Milner and the former Gustrine Caroline Key. He grew up in Birmingham and attended the city's public schools. He earned his degree at the University of Georgia in 1887, followed by graduate studies at Columbia University's School of Mines. During the summers, Milner worked as an assistant engineer for the Birmingham Water Works, helping complete an aqueduct from Five Mile Creek to the North Birmingham Water Works. He also helped supervise construction of the Birmingham Belt Railroad.
After graduating, Milner was employed by the Fort Payne Land Company and helped lay out the city of Fort Payne. In 1888 he returned to the Birmingham Water Works and located the site of the Cahaba Pump Station, the Shades Mountain Reservoir, and the links between them. In 1888 he joined the firm of Milner & Kettig, a mill, mine and furnace supplier which was sold to the Crane Company in 1905. He helped organized the Warrant Warehouse Company and was a director of the American Trust & Savings Bank, the Port of Birmingham Company, and the Magnolia Compress & Warehouse Company of Mobile.
Milner married the former Helen Bishop of Athens, Georgia on February 14, 1899. He was crowned as "Rex Vulcan IV" in delayed Carnival festivities that May. Helen died in 1910, leaving two daughters, Martha and Gustrine. Milner remarried, to Susie Gabard Martin, the daughter of Attorney General of Alabama William L. Martin, on June 2, 1915.
In 1912 Milner organized the Milner Land Company, which developed Milner Heights. He also became a dedicated advocate for economic development, supporting the Alabama Good Roads Association, the Warrior River movement, the Terminal and Transportation Committee, and the Birmingham Chamber of Commerce. He was appointed to the Alabama State Harbor Commission in 1921, headed the American Protective League, and was a vestryman at the Episcopal Church of the Advent. He was an organizer and the first president of the Birmingham Country Club and was also a member of the Roebuck Country Club, the Birmingham Athletic Club and the Birmingham Rotary Club.
- Owen, Thomas McAdory and Marie Bankhead Owen (1921) History of Alabama and Dictionary of Alabama Biography. 4 volumes. Chicago, Illinois: S. J. Clarke Publishing Co.
- Moore, Daniel Decatur (1922) Men of the South: A Work for the Newspaper Reference Library. Southern Biographical Association