An Imperial Protocol Droid, also mistakenly called a Death Star Droid, was a Protocol Droid that may have been used by the Galactic Empire to spy on officials like Grand Moff Tarkin. It is of similar build to C-3PO, but is black. It may have been an attempt at recreating the RA-7 droid seen on the Death Star, as no TC or 3PO droids were seen on the death star (besides C-3PO). This minifigure is exclusive and unique to the set 10188 Death Star.
On the packaging of 10188 Death Star, this droid is labeled as a "Death Star Droid." This is incorrect, as "Death Star Droid" is a more specific term used to refer to an RA-7 Protocol Droid. This droid is either a 3PO-series protocol droid, or a TC-series protocol droid. Of course, if used in a generic sense, it is correct, as it is a droid on the Death Star.