Maege Mormont
The She-Bear, Jeor's sister and Lady of Bear Island, a fierce mace-wielding warrior-widow with a brood of equally fierce daughters (book).
The fuller tale
Maege Mormont rules Bear Island the way the island's carved gate advertises: babe in one arm, axe in the other. Sister to Lord Commander Jeor — she inherited when he took the black and his son Jorah fled in disgrace — she is a stout, grey-haired she-bear in patched ringmail who raised five daughters, most of them to fight, and considers the arrangement unremarkable: on Bear Island, with the men so often at sea against reavers and krakens, the women have defended their own shores for centuries. The books put a spiked mace in her hand and a certain bluntness in her mouth that even northern lords step around.
She answers Robb's banners personally, one of the handful of ruling ladies in his host, and serves through the war's whole northern campaign — the Whispering Wood, the westerlands raids — as one of the Young Wolf's most reliable commanders. Her war's most important assignment is also its most secret: before the Twins, Robb sends her and Galbart Glover ahead into the Neck, ostensibly to raise the crannogmen for his campaign to retake Moat Cailin — and actually carrying witnessed copies of his will, the document naming his heir, into the one country in Westeros no army can search. Whatever the remaining books do with Robb's testament, the She-Bear is one of the two people who know where it sleeps.
Her house is the tale's quiet argument that the North's strength was never only Winterfell: a poor island of fishers and bear-hunters that answers every call in full, loses a generation doing it, and sends the next one anyway. Between Jeor at the Wall, Jorah in exile, Dacey in the host and Lyanna in the hall, the Mormonts thread through more of the saga than houses ten times their size — and Maege, mace on shoulder, is the root of the whole stubborn tree.
The page and the screen
Maege is effectively a book character; the show never stages her, folding Bear Island's presence into her brother, her nephew and — memorably — her youngest daughter, with the island's recent past sketched in a line or two of Lyanna's. The books keep her on the board and alive: dispatched into the Neck before the Red Wedding with Robb's will, she misses the Twins entirely, and her whereabouts — somewhere in the crannogmen's trackless swamps, presumably at or near Greywater Watch — are one of the northern plot's loaded guns. Readers waiting on the will, the Reeds and the North's next act are, in large part, waiting on Maege Mormont to walk back out of the fens.
Their fate — if death has found them, it is written here. Open at your peril.
The chronicle records no death for this soul — they are living when the tale leaves them, or their ending is a page the maesters have yet to turn.