MacFadyen is a Scottish patronymic surname meaning "son of little Patrick". The Celtic prefix "Mac" means "son of", while "Fadyen" is a derivative of the Gaelic Pháidín, meaning "little Patrick". It is a variant of the surname McFadden, which has other variants. People with the surname include:
Allan Macfadyen (1860–1907), Scottish bacteriologist
Angus Macfadyen (born 1963), Scottish actor
Christie MacFadyen, Canadian actress
Donnie Macfadyen (born 1979), Scottish rugby player
Donald Macfadyen, Lord Macfadyen (1945–2008), Scottish lawyer and judge
Elmer MacFadyen (1943–2007), Canadian politician
Ian Macfadyen, (born 1942), British retired Air Marshal
Matthew Macfadyen (born 1974), English actor
Ross Macfadyen, Scottish broadcast professional
Willie MacFadyen (1904–1971), Scottish football player and manager
