Adam Seymour Dickson Duncan (8 June 1852 – 21 February 1940) was an Indian-born English lawyer and a first-class cricketer who played in fourteen matches, mainly for Marylebone Cricket Club (MCC), between 1873 and 1879. He was born in Calcutta, Bengal.
| Format | Matches | Runs | Avg | 100s/50s | Top Score | Catches/St |
| First-class | 14 | 313 | 13.60 | 0/0 | 42 | 5/– |
