John Duncan Forsyth (1886 or 1887 – 1963) was a Scottish-American architect who became prominent in Oklahoma. Based in Tulsa and working in a variety of styles, he was connected with a number of significant buildings around the state.
According to one source, Forsyth was born in 1886 in Florence, Italy; another source says he was born in 1887 in Kingskettle, Fife, Scotland. He was raised in Scotland and studied at Edinburgh College, and at the Sorbonne and L’Ecole des Beaux-Arts in Paris. He came to America in 1908 and was part of the large team of architects who worked on Central Union Station (now the Government Conference Centre) in Ottawa. He trained with various architects including John Russell Pope, and fought in World War I with the Royal Flying Corps before moving to Tulsa in 1921, where he became associated with Tulsa architect John McDonnell He received his Oklahoma architect's license in 1925, and soon thereafter he was hired for what became one of his most famous buildings, the E. W. Marland Mansion in Ponca City. A room in the mansion is now dedicated to Forsyth's work.
Forsyth maintained a prolific practice. He left Oklahoma to serve with the U.S.