Francis Conroy Sullivan (born July 2, 1882, Kingston, Ontario; died April 4, 1929, Phoenix, Arizona) was a Canadian architect.

The only Canadian pupil of Frank Lloyd Wright, Sullivan brought the modernist Prairie School style to Canada, building a number of prominent structures, often in the Prairie Style.

He was an architect for the Canadian Department of Public Works from 1908 to 1911, after which he had an independent practice in Ottawa until 1916. In this capacity he frequently designed schools for the Ottawa Catholic School Board.

Examples of Sullivan's work include: The O'Connor Street Bridge in Ottawa, Ontario, Canada - 1907; 108 Acacia Avenue, Ottawa - 1908; The Banff National Park Pavilion, (with Frank Lloyd Wright), Banff National Park, Alberta, Canada - 1911; Ecole du Sacre Coeur (now School House Lofts), 19 Melrose Ave, Ottawa – 1912; Pembroke Public Library, 237 Victoria Street, Pembroke, Ontario, Canada – 1913; 8 McLeod Street, Ottawa – 1912 - 1913; Horticulture Building, Lansdowne Park, Ottawa – 1914; Francis C. Sullivan House, 346 Somerset Street East, Ottawa - 1914; Patrick J. Powers House, 178 James Street, Ottawa – 1915; Edward P. Connors House, 166 Huron Ave North, Ottawa – 1915; Stonewall Post Office (now the town library), 361 Main Street, Stonewall, Manitoba, Canada – 1915; Church of Ste. Claire de Goulbourne (now St. Clare’s Catholic Church), near Dwyer Hill, Ontario – 1915; Shawville Post Office, 100 Victoria Avenue, Shawville, Quebec, Canada – 1917; Edward J. Kelly Estate, Vilas County, near Eagle River, Wisconsin, USA. – 1925.

Although influenced by Wright, Sullivan's work diverged from Wright's in certain important ways. For example, whereas horizontals predominate in Wright's creations, Sullivan used strong verticals to create tension in his designs.

Sullivan moved to the Phoenix, Arizona, area at the invitation of Wright and died there in 1929.