William McDowall of Garthland and Castle Semple was a Scottish Member of Parliament.
- Occupation
- politician, plantation owner
- Position held
- member of the 15th Parliament of Great Britain, member of the 16th Parliament of Great Britain, member of the 17th Parliament of Great Britain, member of the 18th Parliament of Great Britain
- Citizenship
- Kingdom of Great Britain, United Kingdom of Great Britain and Ireland
- Born
- 1749, November 17, 1749
- Died
- April 3, 1810, May 2, 1810