David McCallum, the actor best known for his role as Ducky on the crime procedural NCIS, has passed away at the age of 90. McCallum portrayed the eccentric chief medical examiner for the first 15 seasons of the show. He died peacefully from natural causes surrounded by his family in New York. McCallum was remembered as a talented actor, a loving father, and someone who was passionate about science and culture. His absence from NCIS is not expected to significantly impact the show's storyline.