John Duncan (1866–1945), often known as John Duncan of Dundee, was a Scottish painter associated with the Symbolist movement and the Celtic Revival. Born in Dundee, he studied at the local School of Art before continuing his training in Antwerp and Paris.

Duncan became known for his richly detailed, imaginative works inspired by mythology, literature, and early Scottish history. His paintings frequently depict Arthurian legends, Celtic saints, and allegorical subjects, rendered with intricate patterning and a decorative, dreamlike quality. Notable works include The Riders of the Sidhe and St Bride.

Alongside his easel paintings, Duncan was involved in mural projects and stained glass design, contributing to the wider Celtic Revival in Scotland. Today, he is regarded as an important figure in late 19th- and early 20th-century Scottish art, admired for his mystical vision and craftsmanship.