Aegon I Targaryen, King of the Seven Kingdoms

From Asoiaf

Aegon I of House Targaryen, known as the Dragon, was king of the Seven Kingdoms.

During the Wars of Conquest Aegon granted Storm's End to his rumored bastard brother, Orys Baratheon, after he had defeated and slain Argilac the Arrogant, the last of the Storm Kings.

Harren the Black, King of the Isles also ruled the riverlands, however he was not well loved and many of the river lords deserted him, first amongst them Edmyn Tully, Lord of Riverrun. Harren and his line perished in the burning of Harrenhal. Afterwards Aegon granted Edmyn Tully dominion of the lands of the Trident.

The last King in the North, Torrhen Stark, known as the King Who Knelt, chose to swear fealty to Aegon rather than do battle. He therefore kept his land and continued to rule as Lord of Winterfell.