Which character is responsible for JJ Maybank’s death before Outer Banks Season 5?

Chandler Groff is responsible for JJ Maybank’s death before Outer Banks Season 5. Groff is revealed to be JJ’s biological father during Season 4 and becomes the central target of the Pogues’ revenge mission.

In the Season 4 finale, JJ finds the Blue Crown and gives it to Groff in exchange for Kiara’s safety. Groff nevertheless murders him. The act is especially devastating because JJ had only recently learned Groff’s identity and briefly hoped to understand his family history.

Season 5 begins with Groff still at large. The official story information describes the Pogues as seeking revenge while trying to recover their future. Groff’s escape, the stolen Blue Crown, and JJ’s death provide the final season with its main conflict.