In a world where crime dramas come and go, few have stood the test of time like CBS’s powerhouse, NCIS. As we approach its 21st anniversary, nostalgia collides with curiosity as fans reflect on the remarkable transformation of their beloved cast members. From timid tech whiz Timothy McGee, played by Sean Murray, to the steadfast leader Leroy Jethro Gibbs, portrayed by Mark Harmon, the journey of these characters has been as gripping as the cases they tackle.