Lyanna Mormont

"Bear Island knows no king but the King in the North, whose name is Stark."

- Lyanna Mormont's most famous quote Lyanna Mormont, the Lady of Bear Island, is a major heroine in the sixth season of Game of Thrones, presented in the North storyline. She is the youngest of Jeor and Maege Mormont's five daughters, and the only one to remain at Bear Island during the War of the Five Kings. She is ten years old at the time King Stannis arrives in the North.

In novels
In the fifth novel, Stannis Baratheon sends out letters demanding the northern lords bend the knee to him. It is Lyanna who sends back a similar response as in the show, refuting his claim. Stannis has no idea who Lyanna Mormont is, and asks Jon Snow to identify her. As in the TV version, Jon says to Stannis that she is the Lady of Bear Island - though inwardly Jon thinks to himself that she actually isn't, because she has older sisters, and wonders why she would be identified as such in the letter.

Following the liberating of Deepwood Motte, however, it seems Lyanna has changed her mind about supporting Stannis, for at least one of the Mormonts - Alysane, Maege's second daughter - joins Stannis in his campaign against the Boltons.

In TV series
'Note: This section might spoil the upcoming events in the currently unpublished The Winds of Winter and/or A Dream of Spring''. Please read at your own risk.'''

Season 6
Lyanna is one of the Northern leaders being visited by Jon Snow, Sansa Stark and Davos Seaworth, who are attempting to rally the North against House Bolton. Sansa and Jon try to flatter her, but Lyanna brusquely brushes them off, demands to know why they are at Bear Island, and questions whether Jon and Sansa are technically even Starks, the former being a bastard and the latter being twice married into enemy houses. She refuses to offer her men to them until Davos steps in. He tells her that the real war is not between different houses, but between the living and the dead - and a divided North cannot hope to stand against the Night King. She agrees to help, but can only offer sixty two fighting men. She personally leads these men when Jon travels to Stannis's old camp.

Lyanna is present when Jon and Sansa parley with Ramsay Bolton ahead of their battle. She doesn't speak, but scowls at Ramsay when he mentions pardoning her and the other Northern lords for their treason. She is not present during the battle itself, and presumably stayed behind at the camp.

After Jon's victory, Lyanna is among those present at Winterfell after the battle. As the Knights of the Vale, the many Northern lords, and the Free Folk bicker, she calls out the Manderlys, Glovers and Cerwyns for refusing Jon and Sansa's call to arms. She then declares that she doesn't care if Jon is a bastard, and is the first of the assembled lords to declare him the new King in the North.