How do you say Miller in Gaelic?

There isn't a direct translation of "Miller" in Gaelic that works perfectly across all dialects. The best approach is to translate the *occupation* rather than the surname. This would depend on the specific Gaelic you're interested in (Scottish Gaelic or Irish Gaelic):

* Scottish Gaelic: The most common way would be Muileir.

* Irish Gaelic: The equivalent would be Muileoir.

These both derive from the word for mill. Keep in mind that surnames often have unique origins and might not translate directly. A person named Miller might have a Gaelic surname unrelated to milling.