Archibald Alexander McBeth Duncan, FBA, FRHistS, FRSE (17 October 1926 – 20 December 2017) was a Scottish historian.
From 1962 to 1993 he was Professor of Scottish History and Literature at the University of Glasgow.
On giving up his professorship, he became Clerk of Senate and Dean of Faculties, retiring from the University in 2000.
Since 2001 he has been Emeritus Professor of Scottish History and Literature, but continued to publish on the history of Scotland in the Middle Ages.