All hail Lyanna Mormont of Bear Island
Lady Mormont appeared from out of the blue this season, specifically when Jon Snow and Sansa Stark asked her for help in their fight to take over Winterfell against Ramsay Bolton. Her army wasn’t big, but she stood behind the two, with a little convincing from Davos Seaworth. As innocent as she looked, her mouth was ferocious and spit daggers in their whole exchange and while it took six seasons for us to witness one of the best charachters that ever was, her speech in the finale crowned the new King of the North.
Young Lyanna damn near stole the show for the entire season.