Season 21 of NCIS marks a historic moment as it’s the first time no original characters appear. This streak ended with the passing of David McCallum, reflecting Ducky’s fate. Notably, Sean Murray’s Timothy McGee and Brian Dietzen’s Jimmy Palmer, although long-standing members, weren’t among the original characters. They debuted in Season 1 but played recurring roles.
Currently, only Dr. Mallard and Sasha Alexander’s Caitlin Todd, who met her demise in the Season 2 finale, are unable to return. However, all other original cast members have potential comebacks. Mark Harmon’s return seems likely, but Abby remains the sole original cast member yet to return since leaving her position. Even if Gibbs doesn’t return, his character will be explored in NCIS: Origins, focusing on his early days with Mike Franks’ squad at Camp Pendleton.
Reintroducing Abby should be straightforward. Given her expertise, any team in the NCIS universe would value her assistance. It would be satisfying to see Abby back in her former lab at the agency’s headquarters. Ultimately, her return depends on the decision of CBS and Pauley Perrette, the actress who portrayed her.