Can anyone recommend a gable fan for a finished space? All I've been able to find seem to be attic fans where the motor etc. are visible.

I'd be putting the fan through a standard 2x4 stud wall near the peak of a cathedral ceiling. Ideally it should have an automatic damper or cover on the exterior side, and be quiet as possible.

Thanks for any suggestions!

Home Depot, Lowe's. They both have them with damper and all of them will have a exposed motor. You can build a ventilated box to cover inside.
The damper is automatic when fan on it will open when off it will close.