Fans of NCIS are debating which two characters are essential to keeping them invested in the hit show. NCIS has been on the air for nearly two decades, and many beloved cast members have come and gone, leaving their characters behind. The series now looks nothing like it did with its original cast in 2003. With Tony, Ziva, and Abby all gone, some fans have struggled to keep going.

Though the show is still the highest-rated scripted drama in the world, that could easily change if too many of the cast members decide to leave. A recent Reddit thread debated which characters are critical to the show’s success.

“Who are two characters whose d3aths would cause you to stop watching?” one fan asked in a thread. “Gibbs and Fornell are mine.”

Both Gibbs and Fornell will be back on NCIS for season 19, but things are getting complicated for Gibbs actor Mark Harmon, who was rumored to want to leave the show in a sh0cking report by The Hollywood Reporter.

Many ‘NCIS’ fans agreed on a single character.

Fans unanimously agreed that Gibbs was the most important character required to make the show work.

“Most of the characters I liked left the show, but if I had to pick two, it would be Gibbs and Mcgee,” wrote one fan.

“Gibbs. “And Gibbs,” wrote another fan.

Though one fan stated that their favorites are Jimmy and McGee, every other fan named Gibbs as one of their two.

This is possibly why CBS was reportedly disappointed when Mark Harmon announced his intention to leave the show after season 18. According to The Hollywood Reporter, the network threatened to cancel the show without him, prompting Harmon to extend his contract for another year.

Season 19 Will Have a Significant Cast Change

It’s impossible to say whether or not Season 19 will be his final, but it’s certainly a possibility.

“With Mark, we take it year by year,” CBS President of Scripted Entertainment told Deadline. “We’d love to have him for as long as he wants to stay.”

NCIS also appears to struggle with keeping its new characters on board. Emily Wickersham, who played Ellie Bishop, left the show after the season 18 finale. She took to Instagram to say her final goodbyes to fans before embarking on a new chapter in her life.

And, while Harmon will appear in Season 19, he will only appear in a few episodes, so the show will have a lot to deal with next year. To compensate for the losses, CBS has brought on two new regulars, Katrina Law and Gary Cole. Gary Cole will make his first appearance on the show, but Katrina Law made her debut as Special Agent Jessica Knight in the final few episodes of season 18.

Mark Harmon, along with the rest of the current cast, will be appearing soon. NCIS returns on Monday, September 20th.