Season 19 has included quite a bit of cast turnover, most notably the aforementioned departure of Mark Harmon as Gibbs. Naturally, that has fans worried that other cast members might leave before Season 20 premieres.

The most likely candidate to exit is Wilmer Valderrama, who has multiple other TV projects in development. Wilmer has been on the show since Season 14, but all of his projects are still in the works, so he doesn't have a scheduling conflict just yet.

Katrina Law recently joined the drama as Special Agent Jessica Knight, and it appears that she and Gary Cole are both sticking around for next season. It's unlikely that CBS would have renewed NCIS without at least Cole on board to anchor the show (and Sean Murray, who's now the longest-tenured full-time cast member after Harmon's exit and David McCallum reducing his role).

The series also stars Brian Dietzen, Diona Reasonover, and Rocky Carroll. Reasonover is also rumored to be leaving, since her character Kasie Hines has been through hard times in the current season. However, CBS still listed her as a cast member in the renewal announcement so it's possible that the turnover might be slowing down for this long-running show.

NCIS airs on Mondays at 9 p.m. EST on CBS.