Chris O'Donnell, known for his role as Agent Callen in NCIS LA, also appeared on Grey's Anatomy almost 20 years ago. He played Dr. Finn Dandridge, a love interest for Meredith Grey. The pair started dating but faced complications when Meredith still had feelings for Derek Shepherd. Despite Derek ending things, Meredith expressed that he was the one for her, leaving Finn hurt. NCIS LA and Grey's Anatomy can be watched on CBS and ABC, respectively.