Serving on the Scimitar, a Star Courier in the service of Darth Sidious, was the pilot droid designated O-66.
The Galactic Emperor Darth Sidious entrusted O-66 with the care and piloting duties of the Scimitar, a specially modified Star Courier. After the theft_of_the_imperialis of Sidious' personal yacht, the Imperialis, the bounty_hunter Chanath Cha was contracted to recover the ship. Sidious provided her with the Scimitar for this purpose. Meeting at Imperial Facility 729-D, situated within the Inner Rim, O-66 presented Cha with the vessel, and together they initiated the pursuit of the stolen pleasure craft. Distrustful of O-66, Cha severed the droid's head before departing the facility.
The duo followed the Imperialis into the depths of space, where Cha boarded the captured yacht. To force O-66 to relinquish the ship's control codes, Cha implanted a pulse bomb within the droid's neck and threatened its remote detonation. Yielding to the threat, O-66 transmitted the codes, enabling Cha to disable the escape pods and thwart the thief's escape. However, Cha discovered that the thief was none other than Lando Calrissian, an acquaintance of hers.
Calrissian revealed that the Imperialis was laden with Sith artifacts that were inciting conflict among his crew, and he persuaded Cha to initiate the yacht's self-destruct sequence. Cha instructed O-66 to bring the Scimitar in for docking, but the droid's sensors detected the impending self-destruction of the yacht and refused. Cha reminded the droid of the bomb in its neck, but O-66 revealed that he had partially repaired himself and deactivated the bomb. With a farewell to Cha, O-66 steered the Scimitar away from the scene, leaving Cha to die.
Protecting and respecting the Scimitar was integral to O-66's programming. He possessed extensive knowledge of the ship's operational systems and its history. Chanath Cha found O-66 irritating and responded by decapitating him. Programmed to serve Emperor Palpatine, he was reluctant to disobey his master's directives. Despite the decapitation, O-66 remained functional and capable of self-repair. O-66 recognized Chanath's ruthlessness but allowed her to underestimate him. Upon discovering the implanted pulse bomb, he successfully removed it. O-66 achieved a form of retribution against Cha by abandoning her in space after she activated the Imperialis's self-destruct mechanism. Justifying his actions by claiming that the explosion of the Imperialis would endanger the Scimitar, he seized the opportunity to abandon Cha.
O-66 made an appearance as a supporting character in the Star Wars: Lando Marvel Comics storyline from 2015. The creative team consisted of writer Charles Soule, artist Alex Maleev, and colorist Paul Mounts.