Mike O'Malley Joins NCIS Season 24 as Torres' Mentor

Mike O'Malley has been cast as Walt Keller, a mentor to Nick Torres (Wilmer Valderrama), in NCIS season 24. Keller will appear in the third episode, titled 'Sleeping Dogs.'

Showrunner Steven D. Binder described Keller as one of Torres' old handlers who is not the most by-the-book guy. The episode synopsis states that one of Torres' retired undercover identities is used to commit a crime, requiring him to get back in touch with Keller.

NCIS season 24 premieres Tuesday, October 6 at 8 p.m. ET on CBS. The episode will also be available to stream on Paramount+.

This casting news comes as NCIS continues to expand its universe. In October 2025, NCIS: Origins season 3 and NCIS: New York will follow at 9 p.m. ET and 10 p.m. ET on Tuesday nights for CBS's fall 2026 schedule. NCIS: Sydney season 4 will premiere sometime in 2027.

Season 24 will see Michael Weatherly reprising his role as Tony DiNozzo on a recurring basis, following the conclusion of NCIS: Tony & Ziva, which was canceled after one season. It will also be the first time since season 5 that Rocky Carroll is not a member of the core cast, as his character Leon Vance was killed off in the show's 500th episode.

Fans will remember that at the end of NCIS season 3, viewers learned that Mike Franks, played by Muse Watson, showed Gibbs the ropes when he joined NIS in the early 1990s. Kyle Schmid currently plays Franks in the prequel NCIS: Origins.