Before NCIS, Mark Harmon had a love for football that could have led him to becoming a quarterback in the NFL. He is best known for his role as Leroy Jethro Gibbs for 19 seasons

The actor is known for his role as Leroy Jethro Gibbs on NCIS, who he played for 19 seasons starting in 2003. Mark made headlines when he made cameos on the new spinoff, NCIS: Origins, which stars Austin Stowell as a young Special Agent Leroy Jethro Gibbs, Kyle Schmid as a young Special Agent Mike Franks and Mariel Molino as Special Agent Lala Dominguez, in October 2024.

The actor is known for his role as Leroy Jethro Gibbs on NCIS, who he played for 19 seasons starting in 2003. Mark made headlines when he made cameos on the new spinoff, NCIS: Origins, which stars Austin Stowell as a young Special Agent Leroy Jethro Gibbs, Kyle Schmid as a young Special Agent Mike Franks and Mariel Molino as Special Agent Lala Dominguez, in October 2024.