For over 18 seasons, Mark Harmon played NCIS‘ fearless leader, Leroy Jethro Gibbs, and even though he’s no longer appearing on-screen — he’s still an exec producer — his legacy continues.

Below, we’ve rounded up what his costars have said about Harmon, who exited four episodes into Season 19, over the years.

Michael Weatherly (Anthony DiNozzo)

“[Harmon is] a very rare person in this business because there’s no assistant, no entourage. Mark is largely just a very straight-forward, approachable, calm, assertive guy. He’s not a people pleaser.” (2009)

David McCallum (“Ducky” Mallard)

“There was always a certain degree of chaos [at one point during the series’ production], but it’s all gone now. Mark was instrumental in putting our house in order—I really thank him for that.” (2007)

Cote de Pablo (Ziva David)

“We were always trying to infuse [scenes] with different things, try something new. Mark has been here for years, and he’s still bringing it.” (2019)

Cliff Lipson/CBS

Pam Dawber (Marcie Warren — and Mark’s real-life wife)

“Mark is for the best of everybody and everything. His ego does not extend. He just wants it all to work.” (2021)

NCIS, Mondays, 9/8c, CBS