Before Episode 400 — Previous 'NCIS' Milestones, Ranked

Meredith Jacobs
NCIS Milestone Episodes Ranked
Jace Downs/CBS; Richard Foreman/CBS; Richard Cartwright/CBS

When NCIS returns to our TV screens with new investigations, it will be in its 18th season — and celebrating another milestone: its 400th episode.

We already know that "very special" hour, according to executive producer Frank Cardea, will focus on how Gibbs (Mark Harmon) and Ducky (David McCallum) met. "A case brings them back to 20 years earlier," he previewed.

10 Heartbreaking & Powerful 'NCIS' Episodes That Left an ImpressionSee Also

10 Heartbreaking & Powerful 'NCIS' Episodes That Left an Impression

We take a look back, from the heartbreaking (Kate's death) to the powerful (Taye Diggs' guest spot).

Ahead of that milestone, we're taking a look back at the previous ones. They've brought a team member on officially, introduced an agent's relative after years of only hearing about him, featured memorable cases, and been among the best episodes of the series. Scroll down to see our ranking, from least to most memorable.

NCIS, Season 18, Fall 2020, CBS