: Dr. Donald "Ducky" Mallard (David McCallum) begins to step back from the morgue, feeling his role has become redundant. He eventually transitions into the role of NCIS Historian , officially passing the torch to Jimmy Palmer.
Season 16 moved away from strictly episodic cases to focus on several overarching narratives: NCIS - Season 16
: After 15 years of rigid adherence to his "rules," Gibbs experiences a significant meltdown. In a shocking departure from his stoic persona, he reveals to his team that he killed the man responsible for the deaths of his wife and daughter. This leads him to burn Rule #10 ("Never get personally involved") as he struggles with the morality of vigilante justice. NCIS - Season 16