Family name Grant-Mills (Grant-Mills 
) , throughout the world, is a very rare surname. The family name Grant-Mills is characteristic of the United Kingdom, where it is a very rare surname, and the United States, where it is an extremely rare surname. Parts of the name also exists independently as a last name Grant, and a last name Mills.
| VARIANT | COUNTRY |
|---|---|
| Grant-Mills | United Kingdom, United States |