| Donald Farquharson | |
| Order: | 8th |
| Office: | Premier of Prince Edward Island |
| Predecessor: | Alexander B. Warburton |
| Successor: | Arthur Peters |
| Lieutenant Governor: | George William Howlan Peter Adolphus McIntyre |
| Term Start: | August 1, 1898 |
| Term End: | December 29, 1901 |
| Office1: | Leader of the Prince Edward Island Liberal Party |
| Predecessor1: | Alexander B. Warburton |
| Successor1: | Arthur Peters |
| Term Start1: | August 1, 1898 |
| Term End1: | December 29, 1901 |
| Office2: | Member of the General Assembly of Prince Edward Island for 2nd Queens |
| Predecessor2: | Augustus Holland |
| Successor2: | district abolished |
| Alongside2: | Donald McKay, Joseph Wise |
| Term Start2: | August 10, 1876 |
| Term End2: | December 13, 1893 |
| Office3: | MLA (Councillor) for 2nd Queens |
| Predecessor3: | himself |
| Successor3: | Samuel E. Reid |
| Term Start3: | December 13, 1893 |
| Term End3: | January 15, 1902 |
| Riding4: | West Queen's |
| Parliament4: | Canadian |
| Term Start4: | January 15, 1902 |
| Term End4: | June 26, 1903 |
| Predecessor4: | Louis Henry Davies |
| Successor4: | Horace Haszard |
| Birth Date: | 1834 7, mf=yes |
| Birth Place: | Mermaid, Prince Edward Island |
| Death Place: | Charlottetown, Prince Edward Island |
| Nationality: | Canadian |
| Spouse: | |
| Party: | Liberal |
| Children: | 7 |
| Residence: | Charlottetown, Prince Edward Island |
| Alma Mater: | University of Prince Edward Island |
| Occupation: | teacher, merchant, and newspaper director |
| Profession: | Politician |
| Cabinet: | Minister without Portfolio (1878–1879) (1891–1898) |
Donald Farquharson (July 27, 1834 – June 26, 1903) was a Canadian politician who served as the eighth premier of Prince Edward Island.
A native of Mermaid, Farquharson had been a teacher and then a businessman involved in wholesale and shipping. He was elected to the legislature as a Liberal in 1876 and joined the government of Louis Henry Davies in 1878 until the Davies administration fell the next year. Farquharson sat in opposition until the Liberals won the 1891 election. He became Premier in August 1898 but, in 1901, he was persuaded to run in a by-election to the federal House of Commons since PEI Liberals hoped that as a former Premier, he would be elevated to the Canadian cabinet guaranteeing the island's representation in government. Farquharson won the by-election but Sir Wilfrid Laurier appointed a westerner to cabinet instead leaving Farquharson on the backbenches until his death in 1903.
During Farquharson's premiership the provincial legislature passed the Prohibition Act (or Scott Act) which implemented a complete ban on alcohol sales and production in the province starting in 1901. It would not be repealed until 1948.