- Star Trek: The Motion Picture
- Star Trek II: The Wrath of Khan
- Star Trek III: The Search for Spock
- Star Trek IV: The Voyage Home
- Star Trek V: The Final Frontier
- Star Trek VI: The Undiscovered Country
- Star Trek Generations
Starfleet Intelligence recruits Chief O'Brien to infiltrate the Orion Syndicate, the Alpha Quadrant's leading organized crime ring, to find a Starfleet informant. Posing as a handyman, O'Brien makes contact with a trio from the Syndicate by repairing a piece of their equipment. After researching O'Brien's fake background, Bilby, the leader of the trio, decides to bring him into his circle of associates.
O'Brien fixes some faulty rifles Bilby procured for Raimus, his superior in the Syndicate. Bilby is so impressed by O'Brien's skills and honesty that he bonds with his new acquaintance, telling him about his beloved family. After Bilby reveals the identity of the informant, he takes O'Brien to meet Raimus. At the meeting, O'Brien is surprised to see that Bilby's boss is accompanied by a Vorta. Later, when he tells his Starfleet contact, Chadwick, O'Brien's assignment is extended so that he may learn why the Dominion is involved with the Syndicate.
Proving himself as a valued member of the team, O'Brien helps his new associates rob a bank. The more time he spends with Bilby, the more he worries about the man and what will happen to him when his assignment ends. O'Brien expresses his concerns to Chadwick, who assures him that Bilby will be safest in a Federation prison — provided Starfleet gets him before the Syndicate. But O'Brien is still troubled by the idea of betraying his friend.
Raimus and the Vorta want Bilby and his team to execute the Klingon ambassador to Farius — using Klingon rifles to make it look as if the dignitary was killed by fellow countrymen. The Dominion hopes this will lead to the end of the Klingon alliance with the Federation. As Chadwick prepares to warn the ambassador, O'Brien realizes that the Klingons will kill Bilby and his men, so he hurries to Bilby's apartment to stop him.
O'Brien tells Bilby that he is working for Starfleet, and reveals the pending Klingon ambush. At first, Bilby refuses to believe O'Brien, but once he does, he insists on continuing with the mission, feeling it is the only way to protect his wife and children from Syndicate retribution for his mistake in trusting O'Brien. Knowing he will be killed, Bilby asks O'Brien to care for his cat, and the two men part for the last time. O'Brien returns to Deep Space Nine saddened that he has sent a friend to his death.