Biography
Thomas Mark Harmon (born September 2, 1951) is an American actor, producer and director. He is known for playing the lead role of Leroy Jethro Gibbs on NCIS (2003-2021), a role which has earned him six nominations at the People's Choice Awards including a win for Favorite TV Crime Drama Actor in 2017. Since 2008, he has also been a producer and executive producer of the show as well as its' spinoff series NCIS: New Orleans. His character of NCIS special agent Leroy Jethro Gibbs was introduced in a guest starring role in two episodes of JAG, and continued on the spinoff show NCIS.
He had a recurring role as Secret Service special agent Simon Donovan in a four-episode story arc in The West Wing in 2002, for which he received an Emmy Award nomination.
One of his first national TV appearances (other than as an athlete) was in a commercial for Kellogg's Product 19 cereal with his father, Tom Harmon, its longstanding TV spokesman. Thanks to his sister Kristin's in-laws, Ozzie and Harriet Nelson, he landed his first job as an actor in an episode of Ozzie's Girls.
He has been starring in television and film since the mid-1970s, after a career as a collegiate football player with the UCLA Bruins.
He's been married to actress Pam Dawber since 1987 and they have 2 sons. His son, actor Sean Harmon, had a recurring role as a young Leeroy Jethro Gibbs on NCIS.
Filmography
Cast Credits

Freakier Friday
Character: Ryan
MOVIE • 2025

NCIS: Origins
Character: Older Leroy Jethro Gibbs (uncredited)
TV • 2024

NCISverse: The First 1,000
Character: Self
MOVIE • 2024

Joe Montana: Cool Under Pressure
Character: Self - Narrator (voice)
TV • 2022

The Kelly Clarkson Show
Character: Self
TV • 2019

The Wild
Character: Self
MOVIE • 2019

All or Nothing: The Michigan Wolverines
Character: Narrator (voice)
TV • 2018

The American West
Character: Self
TV • 2016

The Late Late Show with James Corden
Character: Self
TV • 2015

NCIS: New Orleans
Character: Leroy Jethro Gibbs
TV • 2014

The Arsenio Hall Show
Character: Self
TV • 2013

Certain Prey
Character: Lucas Davenport
MOVIE • 2011

Justice League: Crisis on Two Earths
Character: Superman (voice)
MOVIE • 2010

Weather Girl
Character: Dale
MOVIE • 2009

The Bonnie Hunt Show
Character: Self
TV • 2008

The Megan Mullally Show
Character: Self - Guest
TV • 2006
The Tony Danza Show
Character: Self
TV • 2004

Chasing Liberty
Character: James Foster
MOVIE • 2004

NCIS
Character: Leroy Jethro Gibbs
TV • 2003

Freaky Friday
Character: Ryan
MOVIE • 2003
Crew
Crew Credits

NCIS: Origins
Role: Executive Producer
TV • 2024

NCIS: New Orleans
Role: Executive Producer
TV • 2014

Certain Prey
Role: Executive Producer
MOVIE • 2011

NCIS
Role: Executive Producer
TV • 2003

Boston Public
Role: Director
TV • 2000

Charlie Grace
Role: Producer
TV • 1995

Chicago Hope
Role: Director
TV • 1994