Harmon will return in the flesh for a special crossover event on Tuesday, Nov. 11. For one night only, “NCIS” and “NCIS: Origins” are swapping time slots; the spinoff will air first at 8 p.m. ET, followed by the original series.

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