| John Duncan MacLean | |
| Order: | 20th |
| Office: | Premier of British Columbia |
| Predecessor: | John Oliver |
| Successor: | Simon Fraser Tolmie |
| Lieutenant Governor: | Robert Randolph Bruce |
| Term Start: | August 20, 1927 |
| Term End: | August 20, 1928 |
| Office1: | MLA for Greenwood |
| Term Start1: | September 14, 1916 |
| Term End1: | June 20, 1924 |
| Predecessor1: | John Robert Jackson |
| Successor1: | riding dissolved |
| Office2: | MLA for Yale |
| Term Start2: | June 20, 1924 |
| Term End2: | July 18, 1928 |
| Predecessor2: | John McRae |
| Successor2: | John Joseph Alban Gillis |
| Birth Date: | 8 December 1873 |
| Birth Place: | Culloden, Prince Edward Island |
| Death Place: | Ottawa, Ontario |
| Nationality: | Canadian |
| Party: | Liberal |
| Spouse: | Mary Gertrude Watson [1] |
| Children: | 6 |
| Occupation: | teacher, physician |
John Duncan MacLean (December 8, 1873 – March 28, 1948) was a teacher, physician, politician and the 20th premier of British Columbia, Canada.
MacLean was a practicing doctor in the city of Greenwood when he was elected in the 1916 election to the provincial legislature as a Liberal. He served as minister of education and provincial secretary in the cabinets of Harlan Carey Brewster and John Oliver before becoming minister of finance in 1924. In the election that year, he ran and won in the Yale riding. He also served as Minister of Industries between 1924 and 1928.
MacLean became premier when Oliver died in 1927 at a time when the Liberal government was in decline. He was unable to reverse his party's fortunes, and was defeated in the 1928 election by the rival Conservatives. Later that year he attempted to enter the House of Commons of Canada in a by-election as a Liberal candidate, but was defeated by fewer than one hundred votes. He spent the rest of his life as chairman of the Canadian Farm Loan Board.