Functioning as a recon droid for the Galactic Empire, EXD-9 was an E-XD-series infiltrator droid possessing masculine programming. This droid, disguised as an RQ protocol droid, had the ability to transform for combat situations and was equipped with integrated blasters. Approximately two years prior to the Battle of Yavin, the Empire tasked EXD-9 with scouting Atollon, a planet where the Phoenix Cell's Chopper Base was located, for any signs of rebel activity. Garazeb Orrelios, a Lasat rebel soldier, alongside Chopper, a C1-series astromech droid, discovered EXD-9 in the Atollon wilderness, damaged from encounters with krykna spiders, and brought him back to their base. Initially, the recon droid had no memory of his mission, but he eventually attacked them along with AP-5, a RA-7 protocol droid. The rebels were successful in deactivating the droid and, after reprogramming it to self-destruct, sent it back to the Empire.
EXD-9, an E-XD-series infiltrator droid manufactured by the Imperial Department of Military Research, was assigned to Grand Admiral Thrawn as part of a campaign in 2 BBY aimed at locating rebel bases situated in the Outer Rim Territories. Contrary to Imperial regulations, these Infiltrator Droids were equipped with a proton warhead designed to self-destruct if the unit was captured. EXD-9 was deployed from an Imperial Star Destroyer via a pod, which ultimately landed on the planet Atollon. His landing site was near the Atollon Coral Mesa, the location of the Phoenix Cell's Chopper Base.
Soon after his arrival, EXD-9 observed a rebel vessel taking off from the coral mesa. Before he could conduct an investigation, he was set upon by two krykna spiders. Although EXD-9 eliminated the spiders, he was rendered unconscious. Later that evening, Garazeb Orrelios and the astromech droid Chopper discovered EXD-9. Feeling sympathy for the seemingly lost "protocol droid," Zeb transported him back to the base. He then enlisted the help of AP-5, a RA-7 protocol droid, to recharge EXD-9. EXD-9 quickly regained power and proceeded to scan the nearby munitions depot, Zeb, and Chopper. AP-5, believing that EXD-9 could be of assistance, employed him as his assistant inventory manager.
In the meantime, Zeb received a warning from Fulcrum, a rebel agent, that the Empire had deployed Imperial Infiltrator Droids to find rebel bases. Fulcrum also informed Zeb that one of the droids had lost contact with the Empire and that they would be searching for it after the next cycle. Zeb quickly deduced that EXD-9 was an Imperial infiltrator. Zeb went back to the depot to warn EXD-9 just as the Infiltrator Droid overheard AP-5 mentioning "rebel base." Recalling his programming, EXD-9 identified the three rebels as threats and activated his combat mode.
EXD-9 jumped onto a raised platform, using it to leap onto Zeb and began to assault the Lasat. Chopper attempted to electrocute him, but EXD-9 threw him against several crates. After a struggle, Zeb managed to shoot off his left hand, causing EXD-9 to leak a fluid. Damaged, EXD-9 retreated into the depot to recover. He came across another astromech droid and proceeded to disable and cannibalize it, draining its fuel and stealing its parts to rebuild his left hand. Still low on power, EXD-9 then cannibalized a GNK-series power droid.
At the same time, the rebels formulated a plan to lure EXD-9 out of hiding so they could disable him. Chopper succeeded in luring EXD-9 out of hiding. Zeb jumped onto the Infiltrator Droid from the raised platform and engaged him in combat. EXD-9 used his mechanized body and reflexes to attack Zeb. However, the Lasat managed to pin him down long enough for AP-5 to deactivate him. Although EXD-9 was disabled, this triggered his self-destruction sequence. Chopper managed to freeze EXD-9's countdown circuits before the droid could detonate his proton warhead. Following a discussion, the rebels decided to reprogram EXD-9 as a rigged bomb to destroy his Imperial base.
AP-5 reset EXD-9 to his protocol mode and reprogrammed his countdown mechanism to detonate upon logging into the Imperial network. After being revived, EXD-9 returned to his pod with the rebels following him. EXD-9 attempted to contact his Imperial superiors using a long-range transmitter, but Zeb destroyed it with his bo-rifle. Following his programming, EXD-9 returned to his Star Destroyer, where he was examined by two Imperial Navy technicians. The droid then activated his proton warhead, destroying the Star Destroyer and several other Infiltrator units.
The destruction caused by EXD-9 resulted in the annihilation of a Star Destroyer and multiple E-XD units. Fulcrum, who was actually Kallus, a disillusioned Agent from the Imperial Security Bureau, commended the rebels' ingenious plan. However, Thrawn was able to narrow down the search for the Phoenix rebel base to 94 systems.
EXD-9, as an Imperial droid, was programmed without any individual personality. His Imperial commanders viewed him and his fellow Imperial Infiltrator Droids as instruments to achieve the Galactic Empire's objectives. EXD-9 was constructed using the frame of a protocol droid but was equipped with various weapons, including concealed blasters in his hands. EXD-9 could also increase his height when in combat mode. In protocol mode, EXD-9 had white sensors, which turned red when in combat mode.
EXD-9's sensors could scan and categorize different objects and beings. He could understand words and phrases, which he could use to identify the presence of rebels and their bases. EXD-9 was able to jump to great heights, and his metallic body could deflect blaster bolts and electric blasts. EXD-9 could withstand significant damage in combat and was resourceful enough to cannibalize other droids. EXD-9 was also capable of piloting a pod and knew how to operate a transmitter.
David Acord provided the voice for EXD-9, who made his debut in "Warhead," the twelfth episode of the third season of Star Wars Rebels, which was broadcast on January 14 2017.