Mark Harmon
American actor
Thomas Mark Harmon (born September 2, 1951) is an American actor, writer, producer, television director and former football player. He is best known for playing the lead role of Leroy Jethro Gibbs on NCIS.
He has appeared in a wide variety of television roles since the early 1970s, including as Dr. Robert Caldwell on St. Elsewhere, Detective Dicky Cobb on Reasonable Doubts, and Dr. Jack McNeil on Chicago Hope. He also starred in such films as Summer School, Prince of Bel Air, Stealing Home, Wyatt Earp, Fear and Loathing in Las Vegas, Crossfire Trail, Local Boys, Freaky Friday, and Chasing Liberty.
Harmon played Secret Service special agent Simon Donovan in a four-episode story arc in The West Wing in 2002, receiving an Emmy Award nomination for the role. Harmon's character of NCIS Special Agent Leroy Jethro Gibbs was introduced in a guest starring role in two episodes of JAG. From 2003 to 2021, Harmon starred in the spinoff NCIS as the same character.
Early life
Harmon was born on September 2, 1951, in Burbank, California. His parents were Heisman Trophy-winning football player and broadcaster Tom Harmon and actress, model, and artist Elyse Knox (née Elsie Lillian Kornbrath).
This brief starts where responsible research should: with the source description of “Mark Harmon” as american actor. Everything that follows is an evidence route, not borrowed authority.
Why this record matters
The subject matters to the people & ideas register because the source frames it as american actor. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Biographical claims are most persuasive when dates, appointments and relationships can be traced to records created close to the events described. The source revision retrieved here is dated Sep 15, 2026. The linked authority identifier is Q296774. VIAF identifies the subject as 24802509. The Library of Congress control number is no96052210. 3 of 3 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1951, 2002, 2003 and 2021.
A concise life account rarely captures disputed attribution, private networks or the changing language used to describe a career. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Read biographical claims against dates, named institutions and the cited references. Distinguish a subject’s later reputation from evidence produced during their lifetime.
- Establishing names and roles
- Building a first chronology
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Personal papers, civil or court records, institutional files and the scholarship cited by the source.
Three-step research path
- Establish the record: confirm the title “Mark Harmon”, its source revision and the description used here.
- Expand the search: follow Mark Harmon primary sources, Mark Harmon archive and Mark research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
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This entry incorporates text from “Mark Harmon” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.