Long running series 'NCIS' spawns another spin-off with 'NCIS: Origins,' which delves into Gibbs' early years.

Warning: SPOILERS for the NCIS: Origins two-part premiere “Enter Sandman” are ahead!

In the role of former NCIS lead Leroy Jethro Gibbs, Mark Harmon is a tough act to follow. But it seems he found a worthy successor in NCIS: Origins star Austin Stowell.

LONDON -- Once again, Austin Stowell is having the best day ever — all thanks to him winning the role of legendary TV character Leroy Jethro Gibbs in “NCIS: Origins.” “Since I got this job, it has just been day after day after day of the greatest day of my life,” says Stowell, smiling.

The story of young Leroy Jethro Gibbs is predictable but comforting, a just-fine addition to the "NCIS" oeuvre.

NCIS: Origins is telling a story about Leroy Jethro Gibbs ( Austin Stowell in 1991, Mark Harmon narrating and briefly appearing in the premiere) that fans are completely in the dark about—and we start getting teases about that in the two-part opener.

Austin Stowell is single — and not ready to mingle — after the debut of his NCIS prequel series, NCIS: Origins. “I'm in a relationship with a TV show," Stowell, 39, joked to People on Monday, October 14,

Even the "NCIS" origin story for Austin Stowell has a Cracker Jack opening. The impossibly rugged actor, 39, had tried to clear his mind after his February audition for "NCIS: Origins," the prequel series to the CBS police procedural (premiering Monday,

NCIS: Origins' brings the early days of "Gibbs" back to the screens. Mark Harmon talks about the casting of Austin Stowell for the role of young "Gibbs".

Austin Stowell won the coveted role of young Leroy Jethro Gibbs on NCIS: Origins. Stowell portrays the role made famous by Mark Harmon on NCIS, but you may have seen him in some other high profile roles over the years.

Origins" was no easy task, but Mark Harmon was immediately impressed when Austin Stowell auditioned for the prequel.