NCIS EGO WARS - IT'S A CRIME!

NCIS fan faves Sean Murray and Wilmer Valderrama are butting heads for top billing, according to sources who say the warring wannabes may be outshined by the return of the crime drama's biggest star, Mark Harmon.

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Since Harmon bowed out following Season 19, Sean, 45, and Wilmer, 43, have seen their storylines bumped up significantly and sources say their egos have expanded along with their screen time.

"There's no denying Mark's departure gave their characters room to grow," notes an insider. "But you now have two actors who think they should be the star of the show."