Things haven't been easy for Timothy McGee, but he remains to stay in NCIS, and he finally explained why. As the longest-serving cast member of the CBS procedural, Sean Murray's character holds a special place in so many fans' hearts. While not part of Leroy Jethro Gibbs' original team, it's difficult to think about a time in NCIS's history that McGee wasn't part of. That said, it's no secret that maintaining his place in the show has come with its own set of challenges.