David McCallum's death in 2023 was a major loss for the long-running TV series "NCIS," where he played Dr. "Ducky" Mallard for 20 seasons. An oral history of the show revealed that Scott Glenn, who had been considered for the role of Gibbs, was also considered for Ducky. However, Glenn passed on the opportunity. The article explores the potential casting changes and how it could have affected the dynamics of the show. The team also investigated A-list actors like Harrison Ford for Gibbs, but ultimately Mark Harmon was chosen. Jennifer Aniston was also considered for a role but was not cast.