Mackellar is a surname. Notable people with the surname include:
Dorothea Mackellar, influential bush poet Duncan Mackellar and his identically named nephew, Duncan Mackellar, Junior, both early colonial settlers of the area near Braidwood. Michael MacKellar, former Member for Warringah Patrick MacKellar, British military engineer, 1717–1778
In addition, Mackellar may refer to: Mackellar Girls Campus, a girls' high school in Manly Vale, a suburb of Sydney The Division of Mackellar, an Australian Federal electorate first held by William Wentworth IV
See also McKellar (disambiguation)