BioClone Captain Rex (CC-7567) was an Elite (later Veteran) Clone Officer who served in the 501st Torrent Co. under the command of Jedi General Anakin Skywalker, Jedi Padawan Commander Ahsoka Tano, and Admiral (later Captain) Wullf Yularen.
Rex began as a simple rookiee Clone Officer, yet he was one of the several Clone Officers trained under Alpha 17's Officer Training Program during the beginning of the Clone Wars Era. To whom he was trained by ARC Trooper Alpha (or Alpha 17/"Ace") who also trained Bly, Cody, and Gree.
He fought in many battles with Jedi General Anakin Skywalker, Padawan Commander Ahsoka Tano, and with Jedi General Obi-Wan Kenobi and the 212th Attack Battalion. As well as being placed or assigned to other units and Jedi; and under the command of others as well. (Such as: Luminara Unduli and the 41st Elite Corps., Ki-Adi-Mundi and the 21st Nova Corps., and Rogue Jedi General Pong Krell.)
Rex had many Platoon Sergeants; such as Denal and Coric, and several Specialists (Jesse and Kix). Many of his Platoon Sergeants and Specialists also met their fate during the Clone Wars, but one of his only Lieutenants; Echo, met his fate during the mission to the Citadel Prison on Lola Sayu.
He was often very sensitive, and didn't always follow every order; to whom he knew what was right and what wass wrong; other than the fact that he became very sensitive towards the end of the Clone Wars due to his experiences on Umbara and with the conspiracies revolving around Tup and Fives.
He was also very taditional with having nicknames for enemies like with most earlier Clone Troopers. To whom most later Clones like Tup, didn't really carry-on the tradition of nicknaming enemies.
The "Jaig Eyes" on his helmet were earned after surviving his first battle which resulted in a near-death experience.
Rex's facial appearance consists of having shaved grey-blonde hair, with a small scar under his chin. (He eventually became completely bald and had several wrinkles on his face.)
Both his Phase 1 armor and Phase 2 armor consist of having blue markings with "Jaig Eyes" painted on his helmet, a helmet range-finder (antenna), pauldron, and a kama with blaster pistol holsters; yet his Phase 2 helmet and armor is actually modified Phase 1 armor with Phase 2 gear; which also has wield marks showing proof.
He once wore a set of Phase 1 Galactic Marine armor during the battle of Orto Plutonia, to whom it had similar markings like with his main armor, as well as having blaster pistol holsters.
He also wore a set of microbinoculars during the battle of Umbara.
During the conflict on Onderon, he wore special gear which also consisted of having a range-finder and twin blaster pistol holsters.
Captain Rex is considerably one of the most iconic Clone Trooper characters. (Aside from Commander Cody.)
Rex's perferred choice of weapons are his twin DC-17 blaster pistols, to whom he primarily uses them in the Clone Wars series.
He was also one of the very first Clones to have a unique haircut. (Both chronologically and in the actual franchise.)
Echo and Fives may have been ARC Troopers or Officers, but Rex actually became a Veteran Clone Officer and Echo and Fives were actually Lieutenants.
ARC Officers (or ARC Troopers) usually have a higher position of Clone Officer than Elite Officers, but Rex became a Veteran Officer shortly after ARC Lt. Echo's death.
Rex eventually wore modified Phase 1 armor with Phase 2 gear during the end of the Clone Wars era.
He was also trained by ARC Trooper Alpha (or Alpha 17/"Ace") who also trained Bly, Cody, and Gree.
Captain Rex's name ironically was eventually used for the Disney Star Tours ride droid character RX-24 "Rex"; yet they're both completely different characters.
Rex is often mistakenly refered to as "CT-7567", yet "CT" means, "Clone Trainee" for the Clone Cadets, while "CC" means, "Clone Code" for every other Clone Trooper.
The scar under his chin and his character personality is modeled after Han Solo, who was also an officer under the rank of Captain.
Ironically, an on-going cliche which occurred throughout the first-half of the Clone Wars series resulted in many near-death experiences for Rex, which has since made Rex known as an "invincible" clone as coined by some of the producers of the series.
Rex was first introduced in the Clone Wars film, and has appeared in almost every Clone Wars episode, as well as the majority of comic books, magazines, and novels.