Walder Frey: Three seasons after he betrayed the Starks at the Red Wedding, Walder Frey met his revenge. Using a face she probably stole from the Hall of Faces before leaving Braavos, Arya first fed Frey his sons baked into a pie and then slit his throat — as his son had done to her mother.
Death: Season 6, episode 10 ("The Winds of Winter")