How could NCIS Season 21 honor founding cast member David McCallum, who d1ed on Monday at the age of 90?

McCallum played Dr. Donald “Ducky” Mallard, chief medical examiner-turned-NCIS Historian, for all 20 seasons, most recently appearing (remotely) in the final two episodes of Season 20 last spring.

Following the departure of series protagonist Mark Harmon early in Season 19, he was the show’s final remaining original cast member. (In Season 1, Sean Murray only appeared as McGee.)

“For over 20 years, David McCallum endeared himself to audiences all over the world as the wise, quirky, and occasionally enigmatic Dr. Donald ‘Ducky’ Mallard,” NCIS executive producers Steven D. Binder and David North said in a statement. “But, as much as his fans adored him, those who worked alongside David adored him even more…. Working with him was an honor from the start, and he never let us down. He was, simply put, a legend.”

Ducky has recently been primarily off-screen, allegedly on a book tour across the world; his most recent video consultation was delivered from a stop in Edinburgh. On the one hand, the NCIS writers may opt to do for Ducky what Call Me Kat did for the late Leslie Jordan and simply have him enjoy an ideal off-screen existence.

Alternatively, the popular CBS drama might chose to better honor McCallum – whose acting career lasted nearly 70 years and included noteworthy parts on The Man From U.N.C.L.E., Sapphire & Steel, and other TV shows – by giving the longtime NCIS team member his own emotional sendoff.

If NCIS goes down the latter, sadder path, who do you think should be there to pay their final respects to the good doctor? We have a few ideas, followed by a vote where you can express your opinion…

Mark Harmon as ‘Gibbs’

LAST SEEN: Gibbs was cruising about in his newly finished boat when it went “boom” in the Season 18 finale. After Gibbs, McGee, and company solved the case of a contract assassin hired by a conglomerate to clear the way for an environmentally toxic copper mine in the fourth episode of Season 19, “boss” opted to stay in “the middle of nowhere,” Alaska, where the multi-episode plot had taken him.

CHARACTER STATUS: “There’s this feeling among the writing staff — and I share it — that we left [Gibbs] sort of nowhere but also everywhere,” EP Steven Binder told TVLine a year ago. For example, when I think of Gibbs, I don’t see him in an Alaskan apartment. Instead, I suppose he’s dissolved into pixie dust and is drifting around in the skies until summoned back to duty.”

What better “call to duty” than a quick trip to Washington, D.C. to bid a proper farewell to longtime friend and distinguished colleague “Duck”?

Michael Weatherly as ‘Tony’

LAST SEEN: Original cast member Weatherly’s run ended with the Season 13 finale, when Tony discovered that longstanding romantic interest Ziva David had given birth to their daughter, Tali, years ago – prior to her “d3ath.” Weatherly has frequently teased an NCIS sequel (sometimes even a “Tiva” two-fer), but that has yet to materialize, even in the aftermath of Bull’s cancellation.

CHARACTER STATUS: As detailed in the “Ziva” recap below, Tony and Tali most likely reunited with Ziva in late Season 17. Because both former NCIS agents should be available for any Ducky reminiscences, the series might provide some long-overdue fan service along the road.

Pauley Perrette as ‘Abby’

LAST SEEN: Perrette’s original NCIS career concluded in May 2018 after 15 seasons.

CHARACTER STATUS: After Clayton Revees took a bullet for her during a seemingly random (but not) street mugging, Abby vowed to follow in the MI6 agent’s footsteps by leading a homeless women’s charity. She then returned Reeves’ body to his London home before beginning this new chapter in her life. Abby, like Ducky, was obsessed with science, so it would be strange not to hear from her in some manner in any farewell episode. (She might not be in a scene with Gibbs.)

Cote de Pablo as ‘Ziva’

LAST SEEN: After leaving NCIS at the beginning of Season 11 (ending an eight-season tenure), de Pablo’s enigmatic Ziva surprisingly reappeared in the Season 16 finale, then recurred in a couple of Season 17 episodes.

CHARACTER STATUS: In de Pablo’s mid-Season 17 mini-arc, Gibbs assisted Ziva with the “one thing” she wanted to attend to before reconciling with Tony and Tali: ensuring Adam Eshel’s safety. After thereafter, Ziva informed Gibbs that she had slipped word to Tony to get Tali into hiding, and that she would contact him once he and Tali were safe and settled. So, presumably, the DiNozzo-Davids are back together and doing well. However, having one turn up to honor Ducky without the other could be awkward from a narrative standpoint.

Emily Wickersham as ‘Ellie Bishop’

LAST SEEN: In the Season 18 finale, “Rule 91” (a reference to the Gibbs rule, “When you walk away, don’t look back”).

CHARACTER STATUS: In order to prepare for a super-secret undercover op on behalf of Odette, a former CIA operative and Ziva David’s onetime partner, Special Agent Bishop famously — and abruptly! — dropped on romantic interest Nick Torres and the rest of NCIS at large. While it would be lovely to bring Ellie in “from the cold,” it may cause more closure issues with Nick than any single guest appearance can overcome.

Maria Bello as Dr. ‘Jack Sloane’

LAST SEEN: Bello’s final appearance as forensic psychologist Jack Sloane aired in March 2021, capping up a three-season stint.

CHARACTER STATUS: Jack had intimated that she was quitting NCIS to retire to “Costa Rica”; however, she stayed in Afghanistan after a mission with Gibbs to continue a friend’s work defending young girls from Taliban abduction. It’d be fitting to hear from Jack again after witnessing Ducky’s transformation from Chief M.E. to NCIS Historian.

Adam Campbell as ‘Young Ducky’

LAST SEEN: Campbell made her fourth appearance as Young Donald Mallard in flashbacks early in Season 18.

STATUS OF THE CHARACTER: Alive and well… in the past. But what a lovely touch it would be to include even a quick additional flashback to bring the good doctor’s colorful journey full circle.

Bob Newhart as Ducky’s mentor, Dr. Walter Magnus

LAST SEEN: In the mid-Season 8 episode “Recruited” – the illustrious guest star’s only appearance on NCIS thus far.

CHARACTER STATUS: Still alive and well, though Newhart, aged 94, hasn’t appeared on a TV show since an April 2020 episode of Young Sheldon.