Leland Lewis Duncan, MVO, OBE, FSA (24 August 1862 – 26 December 1923) was an English public servant, antiquary and author.
Duncan was born in Lewisham, where he lived throughout his life, was educated at Colfe's Grammar School, and began a career as a public servant.
For his service in connection with the Coronation of King Edward VII and Queen Alexandra, he was invested as a Member (fourth class) of the Royal Victorian Order (MVO) two days after the ceremony, on 11 August 1902.
His work in this field led to his appointment as general editor on Challenor Smith's 1893 Index of Wills, published by the British Record Society.
The journal Archaeologia Cantiana printed his papers 'The Renunciation of Papal Authority in West Kent, 1534', 'The Rectory of Cowden with a list of Rectors', 'The Will of Abp.