Once known as CC-10/994, Grey was a Clone Captain within the ranks of the Grand Army of the Republic during the period of the Clone Wars. He held the rank of Clone Commander in the battalions overseen by Jedi General Depa Billaba. Following the devastation suffered by Depa Billaba's initial battalion, Grey found himself reassigned to a subsequent battalion, also under Billaba's leadership, alongside fellow Clone Captain "Styles."
By the time that Order 66 was issued, Captain Grey was stationed on the planet of Kaller. As a clone trooper, he was programmed with an unwavering compulsion to obey this order. Consequently, Grey made an attempt to eliminate Billaba, branding her as a traitor against the Galactic Republic. Although the general initially resisted, she was ultimately overwhelmed and killed by Grey's clone troopers.
After the Galactic Empire assumed control, Grey and Styles pursued Billaba's Padawan, Caleb Dume, eventually capturing him on Lahn. Grey began to understand the truth, as he came to the realization that his free will had been suppressed by his programming during Order 66. To protect Dume from the clones who sought to eliminate the young Jedi, he ultimately sacrificed his own life.
Grey, originally designated CC-10/994, served as a Clone Captain within the Grand Army of the Republic. This army consisted of clone troopers who were genetically identical, engineered from the template provided by Jango Fett. Throughout the Clone Wars, Captain Grey, a skilled soldier, served under the command of Jedi General Depa Billaba. As a commander within Depa Billaba's battalion, he experienced significant losses during a battle that took place on Haruun Kal. Grey, along with Clone Captain Styles and other survivors, went on to form a second battalion that was still under Billaba's command.
The first mission for Billaba's new battalion took place on the planet Kardoa, and it involved Jedi Commander Caleb Dume, Billaba's new Padawan. The battalion's objective was to investigate the possibility of a Separatist presence on the planet. As they conducted their search in the canyon of Kardoa, an explosion occurred, resulting in the death of numerous clones. A force of B1-series battle droids then initiated an attack, prompting Billaba's battalion to retaliate. Grey survived the ensuing battle, and with the assistance of Billaba and the rest of the clones, the Separatists were forced to withdraw from Kardoa.
Following the successful completion of their mission on Kardoa, the battalion received orders to reinforce Republic forces on Mygeeto during the Third Battle of Mygeeto. Commander Grey deployed the majority of his battalion before the arrival of Billaba and Dume, and then engaged in combat himself. When Billaba, Dume, Styles, and Stance found themselves trapped on a platform by battle droids, Grey turned back to provide assistance, only to discover that they had already received help from Fenn Rau and Skull Squadron. They returned to their base camp, while the majority of their battalion remained in the field. General Grievous, Colonel Coburn Sear, and a contingent of battle droids launched an attack on the camp, resulting in Stance's death. As he and Styles attempted to fight back against the droids, Grey requested reinforcements. They encountered Dume, who had defeated Colonel Sear, and then assisted Billaba, who was engaged in a duel with Grievous. They forced Grievous to retreat, and later held a funeral for Stance. Soon after the conclusion of their mission, they were assigned to another operation on the planet Kaller.
Kaller was among the final battlegrounds of the Clone Wars. Shortly before the war's end, Captain Grey was stationed on this planet. Billaba led Grey and his fellow clones into combat, with the goal of capturing the compound that General Kleeve was utilizing as his operational base. They eventually drove Kleeve and his forces away, although the Kallerans perceived little difference between Republic and Separatist rule. When Janus Kasmir made a disrespectful remark about the Jedi, Grey defended Billaba, but Billaba graciously chose to establish camp outside of the compound, leaving the Kallerans undisturbed. Grey and his men would light a fire and relax while Billaba trained Dume.
Later, the clone troopers under Grey's command and General Billaba engaged Separatist forces on Kaller after the Separatists launched their own offensive following their defeat at the Battle of Coruscant. Despite receiving reinforcements from All Terrain Tactical Enforcers, the clones adopted a defensive posture against a battalion of B1-series battle droids, as well as DSD1 dwarf spider droids and Armored Assault Tanks. Caleb Dume had not yet returned with reinforcements, causing Grey to question whether the Jedi Commander would arrive in time. Billaba assured the captain that her Padawan would. When Dume arrived, Grey was disheartened to learn that the commander had brought only five clones. The squad, identified by Grey as the experimental unit Clone Force 99, annihilated the Separatist units without assistance from Grey's troops. Grey observed the clone commandos through a pair of electrobinoculars as they eliminated the droid battalion, and he admitted to being impressed by their performance.
Hunter, the squad's leader, advised Billaba to order a counterattack as another Separatist battalion approached. Grey informed the commando that only his Jedi General had the authority to issue orders. However, Billaba concurred with Hunter's recommendation and instructed Grey to initiate the counterattack. As Dume and the members of Clone Force 99 advanced toward the Separatists, Grey received a holographic communication from Darth Sidious, the Sith Lord whom he recognized as Supreme Chancellor Sheev Palpatine, commanding him to execute Order 66.
His secret programming now active, Captain Grey betrayed his Jedi General, attempting to execute her as an enemy of the Republic. Billaba raised her lightsaber in time to deflect the captain's blaster fire. She then disarmed him by cutting his blaster in half before kicking him away. However, the clone troopers under Grey's command had also turned against Billaba, complying with Order 66. Though Dume tried to return to help his Jedi Master, Billaba urged him to run before the clones killed her. The members of Clone Force 99 were confused by the situation; Hunter instructed Tech and Echo to speak with Captain Grey while he and Crosshair searched for the Padawan.
Witnessing Billaba's death at the hands of Grey's troopers led Clone Force 99 to speculate how they could have complied with the order to terminate their general, despite serving her loyally for years. Tech was well aware that the Kaminoans conditioned the clone troopers to be obedient, and therefore deduced that their compliance with Order 66 was indicative of their programming.
The Clone Wars, which Grey inadvertently helped bring to an end, drew to a close shortly after the captain received Order 66 while stationed on Kaller. In the days that followed, Grey and Styles continued their search for Dume in Plateau City, but lost his trail when he drastically altered his appearance and began working alongside Janus Kasmir. After a job went wrong which resulted in the pair getting caught, Kasmir immediately sold out the fact that Dume was secretly the escaped Jedi Padawan, and seemingly traded him to Gamut Key's security in exchange for his escape. Grey and Styles were able to confirm for Key that the boy was, in fact, the Padawan they had been hunting for, and they ordered the Kallerans to hold him in a cell until they could leave the Imperial Garrison at Plateau City to take him in and execute him for treason. Shortly after their message, however, Kasmir, who had a change of heart, broke Dume out of his cell using an IG-RM droid, escaping Kaller.
Grey and Styles maintained a close pursuit, always remaining just one step behind Dume and his new friend. They finally caught up to the pair when they landed on Lahn, where they intended to trade stolen spice for a second ship. As Dume was negotiating with their buyer, the former Separatist general Kleeve, Grey ambushed Kasmir and held him at gunpoint, demanding to know where the Padawan had gone. While Kasmir claimed that he had ditched him as soon as they left Kaller, Grey remained skeptical. Dume overheard the exchange, and fled to allow Kasmir's statement to seem truthful. Grey arrested Kasmir anyway, and began a search across Lahn for Dume's whereabouts. Captain Styles managed to ambush Dume, who had gone with Kleeve to the Farbrooke's Hope, the ship Kasmir planned to acquire, and knocked Dume unconscious.
Styles reported back to Grey, informing him of Dume's capture. While transporting Caleb back to Kaller aboard their Gozanti-class cruiser, Grey and Styles were finally faced with the task of putting an end to their former friend. Dume pleaded for his life, reminding the clones how much they used to look up to Master Billaba and suggesting to them that it was Palpatine, not the Jedi, who had betrayed the Republic when he created the Empire. While he was unable to convince the clones not to kill him, he did manage to buy enough time for Kasmir and Kleeve to catch up to the Imperial freighter in an attempt to rescue him. Dume Force pushed the clones and remotely activated the airlock, escaping into the vacuum outside. After managing to return to the bridge of the freighter, Grey began to have doubts about following Order 66. Despite having sufficient firepower to destroy both the Kasmiri and Farbrooke's Hope, Grey could not help but wonder why the clones had so blindly obeyed Order 66. He brought his concerns up with Styles, who disagreed, seeing the Jedi only as traitors to the Empire. When his protestations went unanswered, Grey decided to shoot the ship's controls with his blaster rifle, crippling the freighter and allowing Kasmir and Kleeve to destroy it with both Grey and Styles on board.
Grey was a seasoned, battle-hardened clone. Until Order 66 took effect, he showed great loyalty to his men and to Billaba. However, as Grey and his men continued to pursue Padawan Dume, he was able to overcome his programming, understand his actions during Order 66, and sacrifice himself and his men to help Dume escape.
Although Grey was impressed by Clone Force 99's abilities, he declined Hunter's advice on launching a counterattack against the Separatists, emphasizing that only his Jedi General had the authority to give him orders. During the battle on Kaller, Grey also expressed pessimism, believing that defeat was inevitable when he learned that Dume had returned with only five clones to provide reinforcement. His loyalty to Billaba ceased upon receiving the command to execute Order 66, which he silently followed.
Grey's initial appearance was in the comic Kanan 1 from 2015, authored by Greg Weisman and illustrated by Pepe Larraz. In the debut episode of Star Wars: The Bad Batch, "Aftermath," Dee Bradley Baker provides Grey's voice. Grey's inclusion in The Bad Batch was a reference to the Star Wars: Kanan comic, as the series premiere depicted the same events.
In Star Wars: Kanan, Grey is depicted as a Clone Commander with red markings on his armor, contrasting with the green markings seen in "Aftermath," where he is a Clone Captain. Additionally, the two media portray the execution of Order 66 differently. In Kanan, Commander Grey receives the order at a campsite at night, shortly after a skirmish with the Separatists, and responds with "Yes, my Lord." In "Aftermath," he remains silent while carrying out Order 66.