M-3PO, also known as Emtreypio or simply Emtrey, was a masculine M-3PO military protocol droid functioning as the quartermaster for Rogue Squadron. Constructed from spare parts of various military protocol droids, he aided the Rogues from their reconstitution in 6 ABY until the Yuuzhan Vong War. Due to his makeshift construction, he possessed the body of a typical protocol droid but featured the head of a spaceport control droid.
On Hoth, Emtrey was assembled by a Rebel lieutenant named Losca with the express purpose of acquiring supplies. He was equipped with specialized programming to facilitate this: a 'scrounger mode' that activated when pressured to find parts. Additionally, he had a peculiar program that deactivated his regular personality and functions after being told to be quiet more than three times. This program essentially transformed him into a 'dumb' terminal providing access to Emtrey's memory stores. Rogue Squadron members utilized both of these features during his tenure with them. Following the New Republic's initial capture of Coruscant, the terminal mode was disabled.
It was subsequently revealed that New Republic Intelligence had secretly incorporated the terminal mode into Emtrey to ascertain whether then Captain Tycho Celchu had been successfully brainwashed into an Imperial agent. This programming, along with other features, transformed Emtrey into a valuable espionage tool that would have exposed Celchu had he been a spy and utilized Emtrey in such a manner. Emtrey was also instrumental in substantiating that Celchu had not met with Imperial agents, contrary to Corran Horn's accusations. The reappearance of Horn, coupled with the betrayal of Imperial mole Erisi Dlarit, definitively proved Celchu's innocence. The special programming was deactivated during the trial, and Corran Horn discerned that he had been assigned to monitor Celchu when the remote mode ceased to function.
Following Celchu's trial and Ysanne Isard's departure for Thyferra, Rogue Squadron members resigned to overthrow the puppet government she had established on that planet. Emtrey, along with all of the squadron's equipment and starfighters, was declared surplus by an individual within the military as a covert means of supporting the former Rogue Squadron members. The former Rogues acquired Emtrey, and he served them in diverse roles. He was later appointed as a liaison aboard the Valiant, a droid ship that survived the destruction of Alderaan.
After Isard's defeat, Emtrey resumed his service with the New Republic.