Bill Inoshita/CBS; Sonja Flemming/CBS; Ron P. Jaffe/CBS
Parminder Nagra (Ella)
Nagra’s guest spot as Ella was memorable for three reasons — it brought the actress to the series, her introduction led to Sam getting shot by a sniper, and it was tied into Thapa’s return.
John M. Jackson (A.J. Chegwidden)
One of the JAG actors who have reprised their roles on one of its spinoffs, he’s an old friend of Hetty’s and memorably knocked out Joelle when the team found out she was a CIA officer during the mole hunt.
Ernie Reyes Jr. (Thapa)
The Gurkha was quite skilled with a blade and memorably offered advice about Kensi and Deeks’ relationship, both in his first appearance in “The Frozen Lake” and his return, “Expiration Date,” which ended tragically.
Timothy V. Murphy (Isaac Sidorov)
He’s been quite the memorable bad guy on CBS procedural dramas. Criminal Minds fans remember Murphy for “killing” Prentiss. NCIS: LA fans remember him for torturing Sam and Deeks at the end of Season 4 and beginning of Season 5.
Claire Forlani (Lauren Hunter)
Forlani’s Lauren Hunter wasn’t exactly welcomed with open arms at OSP, mainly because she was taking on Hetty’s role at the time, but it’s hard to forget her death, trapped in a car as it was blown up.
Ron P. Jaffe/CBS
Alicia Coppola (FBI Agent Lisa Rand)
NCIS fans recognize Coppola as Lieutenant Commander Faith Coleman, a character first introduced on JAG. But on the West Coast, she plays the FBI agent who has worked with the team on some of their toughest cases, including a teenager buried alive (“Little Angels”), a kid brainwashed to wear a suicide vest (“The Seventh Child”), and the still-unsettling “The Monster.”
Carl Lumbly (Charles Langston)
Lumbly’s Langston was part of the old guard and another of Hetty’s friends who made things interesting (by getting in the way) for the team.
James Remar (Sterling Bridges)
Remar guest starred as another one of Hetty’s old friends, and the best parts about his appearances were his interactions with the team.
Vyto Ruginis (Arkady Kolcheck)
There are few guest stars as entertaining as the retired KGB officer is every time he pops up, whether he’s keeping information from the team, trying to help, or interacting with his daughter.
Aunjanue Ellis (Michelle Hanna)
Ellis recurred as Sam’s wife for four seasons, occasionally working with the team (most memorably undercover to take down Isaac Sidorov) until her tragic murder at the end of Season 8.
Ron P. Jaffe/CBS
Gerald McRaney (Retired Navy Admiral Hollace Kilbride)
McRaney first appeared in the Season 6 episode, “The 3rd Choir,” and he returned for a few episodes at the beginning of Season 10. The This Is Us doc was a pleasant addition to OSP for the time we had him, because it was nice to see someone on the team’s side.
David James Elliott (Harmon “Harm” Rabb)
Elliott reprised his character of Harm for the last two episodes of Season 10, as part of a JAG reunion that included that memorable theme during his introduction.
Jeff Kober (Harris Keane)
Everyone thought Keane was dead, until Hetty found him in Vietnam and the two memorably shared a prison with each other — and a tiger.
Catherine Bell (Sarah “Mac” MacKenzie)
Bell was part of the JAG reunion that ended Season 10 — and Mac memorably convinced a Russian diplomat to help them by interrupting him with his mistress and taking photos.
While the NCIS: Los Angeles cast has, for the most part, stayed relatively the same over the years, the CBS drama has also had some memorable guest stars.
Some of these actors have recurred, while others have only appeared once, but however long they stayed around, they left quite the impression — on the show and on viewers.
Click through the gallery above for the guest stars we can't forget from NCIS: LA.