'NCIS' Celebrates 350 Episodes — See How the Cast Has Changed (PHOTOS)

Meaghan Darwish

It's the end of an era for NCIS fans, as Pauley Perrette prepares to leave the long-running CBS series. But before that, the CBS series has something good to celebrate: 350 episodes!

On April 17, the long-running procedural hits the major milestone, reminding us just how much the show and its cast have changed through the years. In fact, Perette isn't the first to make her exit — in the show's earlier years, Mark Harmon was flanked by the likes of Michael Weatherly (Bull) and Cote de Pablo, both who have since left.

Here's What We Know About Pauley Perrette's Final 'NCIS' Episodes as Abby

Here's What We Know About Pauley Perrette's Final 'NCIS' Episodes as Abby

The actress has appeared in over 350 episodes since the 2003 premiere.

Still, a number of favorites are still around, such as Sean Murray and David McCallum. And in honor of the big episode, we're taking a look at the stars who made NCIS what it is today from way back when to now. Click through the gallery above for them all!

NCIS, 350th Episode airs Tonight, Tuesday, April 17, 8/7c, CBS