'NCIS': Will Season 19 Be the Last Ever Season? On 3/17/21 at 12:44 PM EDT NCIS is currently taking a two week hiatus after the huge cliffhanger that Gibbs (played by Mark Harmon) has been suspended. This plot twist, however, could spell the beginning of the end for the CBS show, which has already run for 18 seasons and over 400 episodes. With Mark Harmon's contract for the procedural ending at the end of Season 18, The Hollywood Reporter wrote that the actor had tried to leave the series. However, after being told that if he left the show it would be canceled, he agreed to guest star in a number of episodes of the next season.