Entering its 21st season, NCIS is the third-longest-running drama series in TV history, following only Law & Order: SVU and Law & Order in the number of seasons on the air.
Season 20 saw the changes introduced at the end of Season 18 and beginning of Season 19 come to fruition as Gary Cole (Alden Parker), who took over for Mark Harmon (Leroy Jethro Gibbs), has won over the team—and viewers—as its new leader, and Katrina Law (Jessica Knight) has nicely replaced Emily Wickersham (Ellie Bishop), who exited at the end of Season 18, as the female member of the squad.