Mackellar is the surname of:
- Dorothea Mackellar, influential bush poet
- Michael MacKellar, former Member for Warringah
- Patrick MacKellar, British military engineer, 1717-1778
In addition, Mackellar may refer to:
- The Division of Mackellar, an Australian Federal electorate first held by William Wentworth IV
- Mackellar Girls Campus, a girls' high school in Manly Vale, a suburb of Sydney