"DJ," shortened form of "Don't Join," was the alias of a human male slicer who resided in the galaxy during the war between the Resistance and the First Order. An amoral thief, he spoke with a stutter but was also skilled at slicing into computer systems. His philosophy was influenced by his cynical views; he therefore believed that both sides in the conflict represented two halves of a system breeding corruption and greed.

At the time of the Resistance's evacuation from the base on D'Qar, DJ was residing on the planet Cantonica where he used his skills to steal money from the wealthy patrons of the Canto Bight casino city. He offered his assistance for a price to the Resistance operatives Finn and Rose Tico after learning about their mission to recruit a codebreaker. Although he helped them infiltrate the First Order Navy flagship Supremacy, DJ chose to save his own life after they were captured by Captain Phasma and her stormtroopers.