EV-A4-D, alternatively known as A4-D or Ay-Four-Dee, functioned as an A4 laboratory assistant droid, serving General Grievous, a cyborg within the Confederacy of Independent Systems. He operated as a medical/repair droid during the Clone Wars. Like many droids of the EV model, EV-A4-D possessed a sadistic personality due to a programming flaw. Before his assignment with Grievous, EV-A4-D held a supervisory position in a Tauber hospital, a world. He was removed from this position after instructing the medical droids under his supervision to perform surgeries on patients without administering any pain relief. The InterGalactic Banking Clan later acquired him and incorporated him into the Confederacy's ranks.
Eventually, EV-A4-D was designated as Grievous's personal doctor. He was stationed at Grievous's castle, found on the third moon of Vassek. EV-A4-D took on the role of the facility's caretaker, overseeing the general's residence and repairing any damage Grievous sustained to his cyborg body during the war. In 22 BBY, Count Dooku, the Confederate Head of State, lured Republic forces to Grievous's castle. This was done to evaluate Grievous's capabilities as the Supreme Commander of the Separatist Droid Army. During the confrontation with the Republic forces, Grievous suffered significant damage, prompting EV-A4-D to repair him so he could confront the intruders again. EV-A4-D then separated the two Jedi leading the Republic forces, Nahdar Vebb and Kit Fisto, which allowed Grievous to defeat Vebb. However, while monitoring the castle's security cameras from the control room, EV-A4-D was decapitated and destroyed by Fisto.
Grievous later recovered and reassembled the droid's body. EV-A4-D then departed Vassek, accompanying his master on military campaigns, serving as both a doctor and advisor. EV-A4-D was present with Grievous during the siege of Dorin, where he informed the general about a communication from Asajj Ventress, Count Dooku's assassin.
MerenData manufactured EV-A4-D as part of the first-degree EV-series supervisor droid product line. Like the majority of EV-series droids, A4-D, or Ay-Four-Dee, had a programming flaw during manufacturing that resulted in a sadistic and malicious personality. Despite this defect, MerenData sold the EV-series droids, and EV-A4-D became a supervisor to the droids working as staff in a hospital on the planet of Tauber. EV-A4-D's presence in the hospital dramatically increased the droids' productivity; however, the Human doctors were disturbed by the supervisor droid's methods. After some time at the hospital, EV-A4-D instructed the droids to perform operations on patients without using painkillers. Consequently, EV-A4-D was returned to MerenData, only to be purchased later by the InterGalactic Banking Clan.
During the Clone Wars, the InterGalactic Banking Clan allied with the Confederacy of Independent Systems, a separatist government that opposed the Galactic Republic. EV-A4-D, modified with medical and repair attachments, was assigned to work in the castle of cyborg Confederate General Grievous, who was also the Supreme Commander of the Separatist Droid Army. The castle was located on the third moon of the planet Vassek. There, EV-A4-D served as Grievous's repair droid and doctor. Besides his duties as Grievous's personal physician, EV-A4-D also served as the caretaker of the Vassek facility. He oversaw its daily maintenance, managed the general's IG-100 MagnaGuard bodyguards, and fed Gor, Grievous's pet roggwart. The general was fond of Gor, but he thought that Gor's abilities as the castle guardian could be improved. Thus, Grievous enlisted EV-A4-D's assistance in attaching cybernetic limbs, exoskeletal plates, and armor to the roggwart. As the war progressed, EV-A4-D became accustomed to his master returning from battle needing repairs. At one point, he knew the reasons for Grievous's transformation from a proud Kalee warrior into a cyborg subordinate of Confederate Head of State Count Dooku. This information was eventually removed from his memory.
In 22 BBY, Nute Gunray, a member of the Separatist Council, was captured by Republic forces after a failed attempt to bring Rodia into the Confederacy. Shortly after his capture, Gunray escaped from captivity aboard a stolen Republic frigate. Gunray's escape gave Dooku an opportunity to reevaluate Grievous's ability to lead the Droid Army, which had been questioned after a series of recent defeats. While Grievous was away from his castle, Dooku planted the homing beacon from Gunray's frigate inside the general's lair. He also remotely deactivated Grievous's IG-100 MagnaGuards, leading EV-A4-D to believe that Grievous himself had deactivated them.
After the tracking beacon was placed, Kit Fisto, a High Jedi General, and Nahdar Vebb, a Jedi Knight, arrived on Vassek's third moon with a small group of Republic clone troopers. They had tracked the Republic frigate, hoping to recapture Gunray. Dooku and Gunray revealed their manipulations to the Republic forces through a hologram, which led the Jedi to plan the capture of Grievous instead of Gunray. The group decided to take Grievous into custody when he arrived at his castle. When Grievous returned to his lair, he was ambushed by the Republic forces. During the following duel, Fisto severed the general's legs with his lightsaber, and Grievous's faceplate was damaged by blaster fire.
The general escaped into the castle's control room, where EV-A4-D met him. EV-A4-D reprimanded Grievous for allowing the Jedi to damage him and informed him that his guards had been deactivated. EV-A4-D left to prepare for the cyborg's repairs, while Grievous stayed in the control room to release Gor, hoping Gor could kill the intruders. However, EV-A4-D pulled Grievous away from watching Gor's efforts because he was ready to repair Grievous. In the castle's operating theater, EV-A4-D began removing Grievous's damaged parts, replacing his severed legs with new limbs and painfully lifting off the general's faceplate to put on a new one.
After completing Grievous's repairs, EV-A4-D followed the general back to the control room and informed him of an incoming transmission from Dooku. At that point, Grievous learned of Dooku's deception. This, combined with the Jedi's defeat of Gor, spurred Grievous to hunt down the Jedi himself, despite EV-A4-D's insistence that he rest. While Grievous left to fight Vebb and Fisto, EV-A4-D remained in the control room to monitor the castle's security cameras. When he saw the Jedi trying to enter the control room, EV-A4-D alerted Grievous via the stronghold's speaker system.
Fisto opened the entrance to the control room, but Vebb insisted on staying outside to confront Grievous. While the two Jedi argued about what to do, EV-A4-D resealed the entry to the control room, locking Fisto inside and leaving Vebb outside to face Grievous alone. EV-A4-D happily watched Grievous gain the upper hand in his duel with Vebb and encouraged the general to kill the Jedi. However, the droid forgot about Fisto, realizing too late that he was now locked in the control room with the Jedi. Fisto approached EV-A4-D from behind and destroyed the droid by decapitating him through the control room chair with his lightsaber. Shortly after EV-A4-D's destruction, Grievous killed Vebb, but Fisto managed to escape.
After the Jedi escaped, Grievous found EV-A4-D's destroyed body and had the droid rebuilt. Once repaired, EV-A4-D left Vassek's moon with his master, no longer just doing housekeeping and repairs. In addition to being Grievous's doctor, the droid became an advisor to the cyborg and accompanied him when he was away from the Vassek castle. EV-A4-D was present during Grievous's attack on the Kel Dor homeworld of Dorin in the Expansion Region, where the cyborg general tried to exterminate the native population.
During the later stages of Grievous's initial assault, EV-A4-D informed the general of an incoming transmission from Asajj Ventress, a Confederate commander and Dark Acolyte apprentice of Count Dooku. Although Grievous was reluctant to accept the communication, EV-A4-D convinced him to listen to Ventress, who was relaying a message from Dooku himself. Ventress warned the general about a Republic fleet that had left Coruscant and was heading to reinforce the natives of Dorin. She explained that the fleet was under the command of Anakin Skywalker, a Jedi General who could easily change the course of the battle. Grievous was not deterred by this information and ordered EV-A4-D to begin preparing for the arrival of the Republic fleet.
EV-A4-D showed a cruel personality, similar to other EV-series supervisor droids from MerenData. While he successfully increased the productivity and efficiency of the medical droids working on Tauber, EV-A4-D's practices worried the organic doctors he worked with. His methods eventually led to his dismissal when he ordered the medical droids to deny painkillers to the hospital's patients, causing unnecessary pain to the people the hospital was supposed to help.
After being transferred to Grievous's Vassek castle, EV-A4-D's high-level abilities as a supervisor and taskmaster were not used, as his responsibilities were limited to housekeeping and managing a small force of MagnaGuards. EV-A4-D became bored with his work and desired excitement, a wish that was granted when Fisto and Vebb arrived. Although he was usually very attentive, EV-A4-D became careless during the intrusion, losing track of Fisto and realizing too late that the Jedi was right behind him, ready to attack.
During his time serving Grievous as the cyborg general's personal doctor, EV-A4-D developed an unusual relationship with his patient. Although Grievous usually did not tolerate insolence or disrespect, he endured the droid's criticism of his abilities and demands during repairs. While A4-D worked diligently to ensure quality repairs, he enjoyed the opportunity to inflict pain on the Kaleesh during his reconstructive surgeries. EV-A4-D was curious about the reasons for Grievous's physical transformation and took care to ensure his work on the mechanical body would not be wasted, insisting that Grievous rest after his repairs. The droid was delighted by Grievous's skill during his duel with Vebb, cheering him on just before he was bisected by Fisto's attack.
While most of EV-A4-D's bronze-colored body was similar to other EV-series droids, EV-A4-D had modifications that allowed him to serve as Grievous's doctor. A small attachment hanging over one of EV-A4-D's white photoreceptors housed his logic center. Several arms attached to his torso and back had medical instruments on the ends, while one of EV-A4-D's primary upper limbs had a "carousel arm" that could rotate at the wrist between a surgical laser and a precision gripper. Circulatory fluid used during surgical operations hung from a limb extending from the droid's back. EV-A4-D also had a supply palette attached to his waist and magnetized feet.
EV-A4-D was created for the Star Wars: The Clone Wars series and appeared in the tenth episode of its first season, "Lair of Grievous," which aired on December 12, 2008. However, when the episode originally aired, EV-A4-D was simply known as "A4-D." The droid's full name was not revealed until the episode's Decoded re-airing, which also introduced EV-A4-D's backstory as a hospital supervisor.
The droid was created when Series Director Dave Filoni expressed his interest in having Matthew Wood, the voice of General Grievous, and sound designer David Acord perform in a scene together. The episode's writers decided to have Acord play Grievous's mouthy doctor droid. Wood, Filoni, and Acord brainstormed together on what the droid would sound like, hoping to find a speech pattern as different from Grievous's as possible. Acord eventually chose the distinctive speaking style of Paul Lynde.
In the 2009 Star Wars: The Clone Wars The Complete Season One DVD featurette for "Lair of Grievous," Filoni expressed his regret for killing off EV-A4-D at the end of the episode. The director said he would be interested in bringing back the droid as a disembodied head carried around by Grievous in future episodes of the series. EV-A4-D did eventually return to the series, but not in an episode. Instead, he appeared in a script presented at the Star Wars Fan Days III convention, which served as a prelude to the second season episode, "Landing at Point Rain."
In the Season One Episode Guide included in the 106th issue of the Star Wars Insider magazine—published December 17, 2008—EV-A4-D is incorrectly labeled as R6-H5, an astromech droid. The Galaxy at War sourcebook from Wizards of the Coast contradicts the "Lair of Grievous" decoded episode by stating that the droid is named A-4D and is an A-Series medical droid. This article assumes that Galaxy at War is incorrect.
EV-A4-D is featured in The Clone Wars Animated Comics, a series of short, non-canon videos based on LEGO products. In Episode 4: A Grievous situation, A4-D accompanies General Grievous to Tatooine, where the cyborg was shot down during a dogfight over the planet by Jedi Master Plo Koon. While the general sunbathed in the desert's twin suns, EV-A4-D worked to reattach the limbs his master lost in the crash. The droid was unable to finish before the arrival of Republic forces, causing Grievous's arms to fall off when he tried to duel Nahdar Vebb. Grievous carries EV-A4-D off-screen, where the droid quickly finishes his repairs so the general can return to his duel. Grievous is forced to retreat when Koon arrives to support Vebb, but he leaves EV-A4-D behind with the Republic forces. This video was available on the LEGO Star Wars website, and it allowed viewers to see the story from either the Republic or Confederate perspective.
EV-A4-D also appears in the 2011 non-canon video game LEGO Star Wars III: The Clone Wars, in which he appears in the game's version of "Lair of Grievous." His role as Grievous's repair droid is portrayed humorously, with A4-D forcing the droid General to take a spoonful of medicine. After completing this mission in the Nintendo DS version, A4-D is unlocked for use in the Free Play mode of the game.