Ought-Six was a droid who was the captain of the Droid Crush Pirates of Bestoon, a droid pirate group associated with Bestoon. The Droid Crush Pirates were recruited by the Sith assassin Ochi of Bestoon to hunt the Sith Lord Darth Vader on the planet Mustafar as part of a punishment from Vader's master, Emperor Palpatine. Ought-Six intended to hunt Vader for the parts of his cybernetic suit of armor, but realized that his suit was composed of standard parts. He confronted Ochi and tried to kill him. However Ochi was pulled through a doorway by Vader. While the Droid Crush Pirates forced their way through the door, Vader retrieved his lightsaber from Ochi. The droid pirates were sliced apart by Vader, with Ought-Six being the last to be destroyed. As the droids lay broken on the ground, one remarked that Vader's parts had to be special, but the captain denied it.
He was eventually repaired, continuing to lead the surviving droids of the Droid Crush. Some time later, Ought-Six and the Droid Crush worked alongside the assassin droid IG-88B. At the droid settlement of Zee-Nine City Seven in Hutt Space, the droids assisted IG-88 in a skirmish against Vader and Ochi, who was by then serving the Sith Lord, and Ought-Six was outraged by his former associate's betrayal. After Vader managed to defeat IG-88, the captain recovered the assassin droid's head and fled with his crew, promising to kill Ochi at a later time.
In 21 ABY, Ought-Six and the Droid Crush were employed by Ochi again, this time in the hunt for Palpatine's granddaughter, Rey, who Ochi was to take to Exegol. However, the captain and his crew fought with Zargo Anaximander and his guard droids on Nightside, a station in orbit of the planet Therezar, allowing the family to escape on Anaximander's ship Goldstone with the help of Landonis Balthazar Calrissian and R2-D2. Later, Ought-Six bribed Stiper to allow him on his ship to try and kill Ochi, though the Sith assassin destroyed him, having learned his lesson about employing the Droid Crush to do his dirty work.