Duncan, of Scottish origin, is derived from the Gaelic 'Donnchadh', which means 'dark warrior'. It was borne by several historic figures, including Duncan I, who became King of Scotland in the 11th century. The name Duncan gained significant popularity after Shakespeare's play 'Macbeth' featured a character named Duncan, King of Scotland.
The name Duncan experienced a decline in popularity between 1996 and 2015, with only half as many babies named Duncan born in the latter year compared to the former.