Seezelslak was a bartender of the male persuasion and an Azumel species. He operated Seezelslak's Cantina which was located on the planet of Batuu. Though his clientele was sparse, Seezelslak possessed a love for narrating tales, with one particular story revolving around the Jedi temple in the area, Yoda, and a Padawan called Ady Sun'Zee. In the year 34 ABY, he met Mubo and the droid who used to be Mubo's repair technician; this droid later took on the role of Seezeslak's new procurer of drink ingredients from the Batuu Wilds, following the loss of the previous one. Seezelslak also faced an issue with porgs that Chewbacca of the Millennium Falcon was helping to recover within the walls of his cantina.
When Lieutenant Gauge from the First Order Stormtrooper Corps set up a re-education facility on Batuu, Seezelslak found himself apprehended and forced to become its inaugural subject, with the goal of transforming him into a dedicated follower of the First Order. However, the former repair technician launched an assault on the base with the intention of liberating Seezelslak from the mind-altering process and demolishing the facility. Post-recuperation, Seezelslak quipped that, given his lack of prior formal instruction, the brainwashing techniques would have been ineffective on him.
Bobby Moynihan played Seezelslak in the virtual reality game Star Wars: Tales from the Galaxy's Edge.