CT-66-3339 was a clone cadet who served in Bravo Squad, a training unit, early during the Clone Wars. They were marked with a four on their clone training armor.
CT-66-3339 was a clone of the bounty hunter Jango Fett who was born on the planet Kamino. Like their companions, CT-66-3339 was made to serve in the Grand Army of the Republic. Early during the Clone Wars between the Galactic Republic and the Confederacy of Independent Systems, CT-66-3339 served in Bravo Squad, a squad of clone cadets that trained on Kamino. During their time in training, Bravo Squad managed to complete the practice exam in record time. When ARC trooper Commander Colt of Rancor Battalion arrived to watch over the final exams, Bravo Squad, along with Domino Squad and two other units, were summoned to a hangar in Tipoca City Military Complex for Colt's speech. During the speech, Colt selected Bravo Squad for the final test first as a result of their record time in completing the practice test.
Starting Citadel Challenge version THX variable 1138, CT-66-3339, CT-66-3238, and CT-27-3555 took the right flank while CT-66-3232 and CT-66-3233 took the left flank. CT-66-3232 directed CT-66-3238 and CT-66-3339 to move forward and engage the training battle droids while they followed close behind and the others provided cover fire. The squad moved up and eventually reached the base of the citadel. CT-66-3339 directed CT-66-3238 to move forward to the citadel while the rest of the squad provided cover fire. CT-66-3238 was able to rappel up and capture the light post with CT-66-3339 close behind, completing the exam. While exiting the arena, CT-66-3339 and their teammates passed the approaching Domino Squad and CT-66-3233 mocked them.
CT-66-3339 demonstrated teamwork skills and was able to lead others, directing CT-66-3238 which helped Bravo Squad pass the final exam while also providing cover fire.
CT-66-3339 was equipped with clone training armor which contained the red coloring of Bravo Squad, the number four on their chest plate and left shoulder armor, had their designation on their left leg, and utilized a DC-15A blaster carbine with non-lethal bolts and an ascension cable.
This Bravo Squad cadet's identification number was first depicted in the episode "Clone Cadets" of Star Wars: The Clone Wars. It says 66-3339, and the prefix CT- was predetermined. This way of determining identification numbers was proved with the troopers in Domino Squad.