The Real Reason Behind Ducky's Nickname In NCIS Is Surprisingly Simple

Throughout the first two decades of NCIS, Donald "Ducky" Mallard (David McCallum) was a staple on the series, his nickname so commonplace that it didn't actually get explained on screen. As one of the main characters of the series, Ducky was the chief medical examiner working with the MCRT, and an old friend of Leroy Jethro Gibbs (Mark Harmon). The relationship between Gibbs and Ducky was a special one, as were the relationships between the rest of the MCRT and their wise sage back in the lab. Ducky was always helpful as the team moved through each difficult case.