Clone X troopers, also known as CX troopers, Clone X series, or clone assassins, were specialized clone troopers conditioned by the Advanced Science Division of the Galactic Empire. During the process, their identities were erased and underwent programming to be fanatically loyal to the Empire. Clone assassins were monitored with enhanced tracking to ensure they completed their missions without fail. Acting as specialized clone commandos and assassins active under their own division, they wore unique armor and were equipped with a variety of weapons. In the event of possibly being captured, they were provided with a suicide shocker.
Vice Admiral Edmon Rampart dispatched Clone X to silence clones who knew of Rampart's involvement in the attack on Kamino. Months later, the Empire sent CX-1 to assassinate Senator Avi Singh, and, when CX-1 was captured by the Clone Underground movement, sent CX-2 to silence CX-1 on Teth.
The clone assassin Clone X acts as a sniper on a secret mission for Vice Admiral Rampart.
Clone X troopers, designated as CX troopers and also known as clone assassins, were specialized clone troopers that were activated to serve as assassins and clone commandos. The clones were products of Royce Hemlock's deep undercover program, where clones were conditioned into new warriors without a trace of their old identities. The conditioned soldiers served as special operatives organized under a classified division. In order to avoid detection, only one clone assassin is activated at a time. If a clone assassin fails his mission or is captured, another will be activated and tasked with killing his predecessor.
During operations, Clone X troopers were equipped with black military armor that contained communications devices on the helmets, and could have a rangefinder attached. Their helmet was pressurized and possessed a mechanized visor that would retract and protract as needed. Additionally, a control panel brace could be added for direct control to their CX Dagger vessels. The first three Clone X troopers were provided with a 773 Firepuncher rifle, an RK-3 blaster, and a backpack equipped with thermal detonators, attached to their armor. The four assassins deployed by Hemlock had different helmets and were resistance to stun blasts, Hemlock's own toxin gas, and physical damage as it took a headshot to kill the rest of the assassins. Their weapons included a spear-headed electrostaff, sword-like vibroblades, electrified bolas, and double-barreled blaster pistols. In order to maintain their clandestine nature in the event of being compromised, Clone X troopers had all records of their previous identities (including operating numbers) erased from all databanks and were surgically implanted with suicide shockers to be used in the event of capture and imprisonment as well as a homing device that could avoid scans and remain active while the soldier remained alive.
Several months after the rise of the Galactic Empire, specialized clone troopers were active when one such commando, Clone X, who answered directly to Vice Admiral Edmon Rampart, was ordered to assassinate an Imperial clone trooper known as Cade, who was planning to expose Rampart for his involvement in the destruction of Kamino and its cloning facilities. Set up upon a rooftop near 79's, a cantina on Coruscant that catered to clone troopers, Clone X shot and killed Cade as he exited the cantina alongside clone stormtrooper Slip. Clone X attempted to terminate Slip as well, but the panicked clone managed to commandeer a speeder bike and escape.
Soon after, Clone X managed to track down Slip and successfully assassinate him in the streets of Coruscant after spotting the trooper speaking with Pantoran Senator Riyo Chuchi. In an attempt to tie up any loose ends, Clone X proceeded to attack the senator and her bodyguards, and pursued them through a nearby warehouse. After killing all of Chuchi's men, Clone X prepared to kill the Pantoran senator but was stunned by rogue Clone Captain Rex, who had showed up to extract Slip before his demise. Clone X later awoke to find that Rex and Chuchi had brought him to Trace Martez's repair shop, on Level 1313 of the Coruscant Underworld. After refusing to answer any of Rex's questions, Clone X revealed his knowledge of Rex's name and told him that he was fighting the wrong battle, calling him "limited". The assassin then proclaimed himself as a "believer" before biting down on a suicide shocker, killing himself instantly.
Some time later, Clone X's body, now on a hoversled, was shown to the rogue commandos of Clone Force 99, with Rex mentioning that the assassin's identifying number had been wiped. Six months later, a clone assassin was present at Mount Tantiss, briefly watching a group of clones being escorted by commandos before entering a turbolift. The genetically defective clone commando Crosshair was initially admitted into the clandestine division, but their conditioning attempts were unsuccessful, likely due to his defective nature.
Over six months later, another clone assassin, CX-1, was sent to assassinate former Separatist Senator Avi Singh, who had gone into hiding after the occupation of his planet by the Empire at the end of the Clone Wars. The disgraced Senator was meeting with Imperial Senator Riyo Chuchi, to discuss a potential rebellion against the Empire, and were guarded by rogue clone Captain Rex and several members of his Clone Underground. CX-1 infiltrated the tea parlor where the meeting was taking place and prepared to assassinate Singh, but was compromised at the last moment by Rex. CX-1 tossed a thermal detonator into the room to cover his escape, but was pursed to the top of a maintenance tower, where he was stunned unconscious by another rogue clone trooper. Not wanting a repeat of suicide, the Underground members successfully removed CX-1's suicide shocker and recovered a data puck from his gear containing a list of hit targets. CX-1's capture and inability to kill himself resulted in Clone Commander Scorch deploying another assassin, CX-2, to kill him off. CX-2 travelled on his CX Dagger vessel to the Clone Underground's hideout on the planet Teth and infiltrated the base. After killing several guards, CX-2 then eliminated CX-1 just as his interrogation finished. CX-2 then continued to engage the Clone Underground members, killing multiple and causing the base to collapse from detonators he had planted earlier. Concurrently, Commander Scorch had dispatched a strike team to reinforce CX-2, led by Clone Commander Wolffe, to recover Omega, who was discovered with Clone Force 99.
Upon the arrival of reinforcements, CX-2 disregarded Wolffe's orders to capture Omega alive and continued to operate separately from the strike team, and kept his blaster set to kill while Wolffe ordered his troopers to set their blasters to stun. Despite the animosity between the two clones, CX-2 claimed that his efforts had prevented the target from escaping. CX-2 later engaged in hand-to-hand combat with rogue sharpshooter Crosshair, angered at his inability to become a clone assassin due to his defective nature. Crosshair ultimately defeated CX-2, though he survived the fight.
As the Bad Batch breached Tantiss Base and Hemlock needed to divert his troops to attempt retrieving the broken out Zillo Beast, he decided to activate the rest of his clone assassins, Sniper CloneX3, Sniper CloneX4, Sniper CloneX5, and another trooper. Arriving in the the training room, Hemlock opened the doors of the stasis chambers, with his assassins stepping out into the room, armored and equipped with their unique weaponry. CX-2, Sniper CloneX3, Sniper CloneX4, and Sniper CloneX5 we're then sent to the hangar to deal with the Bad Batch infiltrating. Neutralizing the threat, they brought the Bad Batch back into the training room, where Hemlock began torturing them in an attempt to turn them into operatives. As CX-2 and one assassin remained in the reconditioning room, other assassins went off to the training room just below to neutralize the freed prisoners. Later, Omega snuck into the reconditioning room and was caught, but not before managing to free one of Wrecker's restraints. The other assassins battled Echo and the escaped clone prisoners battled several of the assassins, inflicting heavy casualites and eventually forcing them to surrender.
As Wrecker awoke, he freed himself and knocked out Scorch, CX-2, a clone assassin, and Hemlock. The clone assassin attempted to neutralize him, but Wrecker managed to overpower him and knocked him into a recovering CX-2. As Scorch and Hemlock escaped along with kidnapping Omega, Wrecker pushed the assassin through the window down into the training room. Hunter grabbed the electrospear and tried to find CX-2, but his sight was blurred due to previous torture. CX-2 attempted to sneak up behind Hunter and tried to shoot him. As he approached Crosshair's restraining chamber, he pulled the trigger but missed as Crosshair kicked him at the side. This caused Hunter to able to locate CX-2 using his heightened senses and threw the spear at CX-2, impaling his chest and killing him.
Meanwhile, as Wrecker and one assassin fell into the training room, Echo knocked out one of the assassin by grabbing the other assassin's hand with the blaster and shot him. The assassin got up but sustained more shots from Wrecker, therefore killing him. Echo returned the favor, killing the assassin behind Wrecker with a flurry of lasers. As the two fought the two remaining clone assassins, Wrecker was shot in the leg. He managed to get up and kill an assassin who had managed to sneak up behind Echo by slamming his head into a wall. As the final assassin attempted to attack the disoriented Echo, Vik shot the assassin multiple times, killing him.
- Star Wars: The Secrets of the Clone Troopers