The Master Codebreaker was a codebreaker, a male human, known for his association with the Pirate Queen, Maz Kanata, and his fondness for games of chance.
At some point following Supreme Leader Snoke's rise to power within the First Order, the Master Codebreaker pilfered the Smuggler's Guide from the Kanjiklub chief during negotiations concerning the control of territories in the Rim. He then considered if Maz Kanata had intended the book as yet another test of his intelligence. Prior to attempting to decipher its secrets, the Codebreaker made a trip to the betting parlors of Hosnian Cardota, where he engaged in games with arms dealers, systematically reducing their financial resources. One of these dealers eventually attempted to poison him, but the toxin was neutralized by a hullepi-culture tongue sheath. He then claimed to have departed the parlor from the 350th-floor balcony via a para-wing glider. The Master Codebreaker then went back to the puzzle of the logbook and inscribed an entry detailing this exploit in the Smuggler's Guide.
After his experience on the Hosnian system, the Codebreaker realized that Maz's roster of influential crime syndicates was outdated by decades, and that she failed to mention the true powers of the galaxy. He then added a revised list of powerful syndicates to the Smuggler's Guide: Black Sun was removed from the list; the Crymorah Syndicate was superseded by Droid Gotra; Crimson Dawn was replaced by Son-tuul Pride and the Guavian Death Gang; the Pykes and Hutts were superseded by Kanjiklub and the Red Key Raiders. He also incorporated corporate entities that Maz had omitted: Sienar Fleet Systems, BlasTech, Kuat Drive Yards, Mining Guild, and Corporate Sector Authority.
Taking a break from ciphers to make some credits, though he also said he wouldn't be against a Chandrilan cocktail, the Master Codebreaker ventured to the Brentaal Trading Houses on Brentaal IV, one of the few worlds where the Codebreaker could still indulge in games of chance, which he documented in the logbook.
Following his time on Brentaal and parts spinward, he resumed his efforts to unravel the secrets of the logbook, suggesting that it might be bio-hexacrypted and that he only needed to identify the biological sample Maz used for encryption to decipher it. He also noted that regardless of which power held sway, be it the Galactic Republic or the Galactic Empire, the New Republic or the First Order, business interests maintained their control over manufacturing. Ultimately, the Master Codebreaker succeeded in decoding the meaning of the logbook, concluding that it was an elaborate cipher that the Codebreaker claimed meant "Happy Fete Week," wondering if it was an elaborate way by Maz to wish him New Year Fete. He documented his attempts to decode the Smuggler's Guide within it.
Later, the Master Codebreaker attempted to return the Smuggler's Guide to Takodana as a gesture of gratitude to Maz, deciding to place it aboard the Millennium Falcon. He managed to locate the YT-1300f light freighter and secretly stowed the logbook on board, assuming Han Solo wouldn't notice it. The book was subsequently discovered by Gannis Ducain.
Rose Tico and Finn sought out the Master Codebreaker during a mission aimed at preventing the First Order's flagship, the Supremacy, from tracking the Resistance through hyperspace. Kanata had dispatched them to him, as they were in dire need of someone with his particular skill set. Upon locating him at the Canto Casino in Canto Bight, they attempted to approach him, but were apprehended by the Canto Bight Police Department for illegally parking their starship on the beach. The Master Codebreaker's companion, a woman known as "Lovey" who aspired to his title, inquired about the commotion, to which he responded that he believed it to be of little significance.
The Master Codebreaker was exclusively known by his title, maintaining the secrecy of his true identity. However, he once posted all of his personal data to a public node, encrypted using bio-hexacrypt, declaring that anyone who could decipher the information was welcome to assume his mantle. Nevertheless, no one is known to have successfully retrieved the information.
Mirroring his penchant for secrecy, the Codebreaker's companion concealed her real name from him, and he only referred to her as "Lovey." At the Canto Casino, the Master Codebreaker was restricted to playing dice games and was prohibited from engaging in electronic entertainment. He habitually wore a brooch in the form of a red flower, specifically a plom bloom, pinned to his lapel, which Maz had mentioned to Finn and Rose as a distinguishing feature. On the day the pair sought him out, he sported a thin black mustache.
The Master Codebreaker is a character conceived by Rian Johnson for the 2017 film Star Wars: Episode VIII The Last Jedi. He was played by Justin Theroux, who secured the role just one day before filming commenced.
In earlier drafts of the film's screenplay, Finn and Rose encountered the Master Codebreaker within a cabaret room of the Canto Casino. The Codebreaker enlists their assistance in stealing jewels from an insectoid warlord known as the Butcher of Brix. The trio ascends to the casino's rooftop with the intention of infiltrating the warlord's room, but are detected by a surveillance droid. The Codebreaker is abducted by a "taser beam" from a massive prison ship, and Finn and Rose are apprehended by the Canto Bight Police Department. Jason Fry, the author of the film's novelization, initially desired (along with Johnson) to incorporate this alternative meeting between the Codebreaker, Finn, and Rose to subvert audience expectations. However, it was ultimately decided that presenting a drastically different version of a significant scene would be too disruptive, leading to the abandonment of the idea.