Cay Ploon Kett was an individual incarcerated by the Galactic Empire along with numerous others, an event that transpired roughly four years prior to the Battle of Yavin.
The designation "Cay Ploon Kett" initially surfaced in Star Wars Rebels, specifically in the twelfth episode of the first season entitled "Rebel Resolve." The name, remarkably akin to "K. Plunkett," was visible in Aurebesh on a file containing prisoner information.