Stannis Baratheon
Robert's dour middle brother, Lord of Dragonstone: humorless, rigid, and unbending in his sense of what is owed him by right and law.
A soul of House Baratheon, born at Storm's End.
The fuller tale
Season Two
Robert's younger brother and, by his own reading of the law, the rightful king now that Joffrey is a bastard by another name. He rejects the Seven for the Lord of Light at Melisandre's word, burns the old statues on the beach at Dragonstone, and lets her use him to birth something in a cave that walks into Renly's tent and kills him without a mark to show for it. He sails on King's Landing with the larger fleet and loses the city anyway, to wildfire in the bay and a Tyrell army arriving behind him — the battle ends with his ships burning and his ambitions back where they started, alone on Dragonstone.
Season Three
Diminished after the Blackwater and short on men who still believe the fire was a sign rather than a defeat. He lets Melisandre go looking for king's blood elsewhere and locks up Davos for trying to stop Gendry from being bled for it, though it's Davos who teaches himself to read in that cell and Davos he pardons when letters from the Wall about walkers in the snow finally convince him the war worth fighting is not the one against the Lannisters.
Season Four
Broke and short on swords, he sends Davos to the Iron Bank in Braavos and comes back with just enough coin and just enough of a fleet to matter again. He marches what's left of his army to the Wall, arrives at Castle Black in the middle of Mance Rayder's assault on the gate, and breaks the wildling host from behind with cavalry the Night's Watch never could have raised on its own. It buys him men, a foothold in the North, and a debt from Jon Snow he intends to collect.
Season Five
At the Wall through the worst of the winter, trading with Jon Snow for supplies and swearing he means to take the North for the family rather than for himself. He has Mance Rayder burned for refusing to kneel, and it is Jon's arrow that ends it mercifully instead. He marches on Winterfell against Davos's counsel, loses men and horses to snow and desertion, and lets Melisandre burn his own daughter Shireen alive to turn the wind — it does not save the campaign. His army broken outside Winterfell's walls, he is found alone in the trees and killed by Brienne of Tarth, who has waited a long time to collect on Renly's death.
How it ends for them
On the screen. Fell at Winterfell (S5·E10)
The last of his army broken before Winterfell's walls, his daughter's ashes behind him, Stannis was found wounded against a tree by Brienne of Tarth. She named her charge — the murder of Renly — and he answered 'Do your duty,' and she did.
In the show, the end comes as a ledger being balanced. His sacrifice of Shireen buys a thaw and costs him half his army by desertion and his wife by her own hand; Melisandre abandons him last. He marches the remnant on Winterfell anyway — because the alternative is that the price was paid for nothing — and the Bolton host breaks it in the field. Wounded against a tree in the snow, he is found by Brienne of Tarth, who has waited years to name the charge: the murder of Renly, by blood magic and a shadow. Stannis does not dispute it. 'Do your duty,' he tells her, and she does. The camera looks away at the last — a famous ambiguity the show later closes by confirming his death.
In the published books Stannis is alive — entrenched in the snows outside Winterfell, planning battle, with Shireen unburned at Castle Black and Melisandre far from his side. A letter reaching Jon Snow claims Stannis is dead and broken; the letter's author is Ramsay Bolton, and nothing in it is verified. The books' readers hold their breath on a battle not yet fought.
Their chapters, book by book
A Clash of Kings 6 chapters that name them
A Storm of Swords 4 chapters that name them
A Dance with Dragons 6 chapters that name them
Where the page and the screen part
No principal character divides book readers and show watchers more sharply. The books' Stannis — dry, precise, bleakly funny in a way he himself never notices — is a serious contender for the best military mind in the story, and his Dance with Dragons campaign is a study in adaptation and grit. The show compresses him toward his worst hour: the humor is pared away, the northern strategy shrinks to a doomed slog, and choices the books frame as Melisandre's temptations become his own decisions, made onscreen with open eyes. Book partisans call the show's version character assassination; the show's defenders point out that the books load the same gun — the tellings disagree about whether Stannis fires it.
Smaller divergences ripple outward. Book Stannis never burns men for apostasy at Dragonstone quite as the show stages it; his brother's shadow is dealt with at Storm's End in front of witnesses the show trims; Renly's peach, Proudwing the hawk, and the bleak wedding-night arithmetic with Selyse are all book textures the show never touches. And the show's Stannis loses his campaign before Winterfell entirely, while the books leave him mid-move on the board — with a letter claiming his defeat that the fifth book pointedly declines to confirm.
Their journey
Where the two tellings send them to the same place the road runs whole; where they part, the screen keeps the left and the books the right.