Sean played a Young Gibbs on NCIS during flashback scenes, and many fans thought he was great in the role. He seemed like the obvious choice to play Gibbs again on the new show, but Sean has helped create the show and serves as an executive producer.

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

This is a story I don’t tell. This is the story… of her.” With those few words from Mark Harmon’s narrator Gibbs, CBS’ NCIS: Origins (airing Mondays at 10/9c) raised millions of eyebrows and got people looking at the prequel spinoff n a new way.

Origins is great news for the franchise after his NCIS exit, but it also sets up a big problem for the prequel.