Cindy Ord/Getty Images for SCAD aTVfest 2019
Derek Sheperd's fourth sister is finally making her Grey's Anatomy debut.
Amy Acker, star of The Gifted, Angel, and Person of Interest has been cast to play Kathleen, the one Shepherd sister we haven't yet met, E! News has confirmed.
She'll make her debut in the upcoming Amelia-focused episode, and we'll hopefully finally learn a little bit about the mysterious Kathleen, who is a doctor like the rest of her siblings, though she specializes in psychiatry.
Amelia is the only Shepherd sister who has stuck around on the series, and we've met Liz (Neve Campbell) and Nancy (Embeth Davitz) in past seasons. Kathleen is the only remaining piece of the puzzle.