The “NCIS” family, both on and off-screen, is preparing to bid farewell to one of their own. David McCallum, the cherished actor who embodied the quirky genius of Dr. Donald “Ducky” Mallard for two decades, passed away in September at the age of 90, leaving an irreplaceable void. The show is now set to honor the legendary actor in a special episode that promises to be both heartwarming and poignant.