Mark Harmon, who spent 18 seasons on "NCIS," is reprising his role as special agent Leroy Jethro Gibbs for a crossover event.

Mark Harmon will reprise the role of Leroy Jethro Gibbs in an upcoming episode of “NCIS: Origins.” Harmon, who played Gibbs ...

This will be Stowell’s first episode working with Campbell; the actor played young Ducky in four NCIS episodes, and on the mothership, young Gibbs was played by Sean Harmon (who is an exec producer on ...