This article contains plot spoilers for the 2017 series of Twin Peaks.
Robby was a guard hired by Buella.
Robby guarded the door at Buella's home. When Cooper approached the front door, Robby raised a shotgun, only to be hit in the face by Cooper. After regaining composure, Robby followed Cooper inside for some retaliation. As he raised his gun to hit him with the stock, Cooper hit the stock, causing the gun's barrel to knock him unconscious. Cooper informed Buella that she needs a better doorman, to which she replied "It's a world of truck drivers."