Mark Harmon is 74 years old as of early 2026.

Quick Scoop

  • Mark Harmon was born on September 2, 1951, in Burbank, California.
  • Multiple entertainment bios and fan sites list him as 74 years old, which matches that birthdate in 2025–2026.
  • He is best known for playing Leroy Jethro Gibbs on the long-running TV series “NCIS,” which made him a staple of crime drama TV.

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