Aegon IV Targaryen, the eleventh man to sit the Iron Throne and remembered ever after as Aegon the Unworthy, was the eldest son of Prince Viserys, later King Viserys II, by his Lysene wife Larra Rogare. He was born in King's Landing in the third moon of 135 AC and grew up during the reign of his great-uncle Aegon III, for whom he was named. As a young prince he was handsome, vigorous, and clever, skilled with lance and sword and quick of wit, the brightest light at court; but he could not rule himself, and his lusts, gluttony, and appetites ruled him in his place. By the end of his life he had grown so bloated and morbidly obese that his legs could not bear him and his eyes were near lost in the fat of his face. In 153 AC his father wed him to his own sister, Princess Naerys, a pious, gentle, and frail woman whom Aegon loathed and made miserable; she bore him his heir, Prince Daeron, on the last day of that year, and after a second perilous childbed begged to live as brother and sister, which Aegon refused. Naerys found her solace in the company of their brother Aemon the Dragonknight, whose fame and virtue Aegon resented all his days.
Aegon's road to the throne ran through the deaths of his kin. He rode with his cousin Daeron the Young Dragon in the conquest of Dorne, and later, when Baelor the Blessed shut Princess Daena and her sisters away in the Maidenvault, it was Aegon who helped Daena escape her confinement and got upon her a son, Daemon, the first of his bastards to be acknowledged among many. After Baelor starved himself to death and Daena was passed over in the succession, Aegon's father Viserys II ruled but a single year before dying suddenly, and rumor whispered that Aegon had poisoned him to hasten his inheritance. In 172 AC the crown passed to Aegon, the Fourth of His Name.
His reign is reckoned among the worst in the history of Westeros. He filled his court not with the wise or honest but with those who flattered and amused him, gave away the rights and treasures of one house to gratify another, and took as he pleased from highborn maidens and common women alike, boasting at the last that he had bedded nine hundred women whose names he could not remember. He kept nine mistresses he claimed to have loved, among them Falena Stokeworth, Megette, Cassella Vaith, Barba Bracken, and Melissa Blackwood, and fathered a swarm of bastards upon them. To honor and then to spite his Bracken and Blackwood lovers he renamed a pair of disputed hills first Barba's Teats and then Missy's Teats, a slight the two houses quarrel over still. He gave the Valyrian steel sword Blackfyre, the blade of the Conqueror, not to his trueborn heir Daeron but to his bastard Daemon, whom he knighted at twelve, and tongues began to wag that Daemon might be made his heir. When the knight Ser Morgil Hastwyck accused Queen Naerys of adultery, Aemon the Dragonknight defended her honor in trial by combat and slew him, though Maester Kaeth in his Lives of Four Kings held that Aegon himself had started the rumors. In 178 AC Aegon caught his Kingsguard knight Ser Terrence Toyne abed with his mistress Bethany Bracken and had them both put to death, along with Bethany's father; the Toyne brothers sought vengeance, and Aemon the Dragonknight gave his own life to shield the king from their assassination attempt. Naerys herself died in childbed the next year, and Aegon, freed of both his brother and his wife, dared at last to cast doubt on the legitimacy of his own son. His attempts to conquer Dorne came to nothing, his great fleet scattered and wrecked by storm, and his command that the pyromancers build him mechanical dragons of wildfire burned away a quarter of the kingswood and many of their lives.
Aegon's unworthy reign ended in early 184 AC, when at only forty-nine he died a horrible death, so fat he could no longer walk, his rotting limbs crawling with worms while the maesters looked on in disbelief. His last act was the most ruinous of all: upon his deathbed he issued a decree legitimizing all his bastard children at a stroke, the Great Bastards among them. The bitter fruit of that decree was the line of Blackfyre Pretenders and five generations of rebellion and bloodshed, so that some chroniclers laid the long decline of House Targaryen at the feet of Aegon the Unworthy alone.