Maekar I Targaryen, the first of his name, was born in 177 AC, the fourth and youngest son of King Daeron II and Queen Myriah Martell. Grim, proud, and dour, with a soldier's temper and little love for the courtly graces, he chafed all his life at standing in the shadow of his brothers, above all his eldest brother and the realm's darling, Prince Baelor Breakspear. He was granted the seat of Summerhall and styled Prince of Summerhall, and he wed Lady Dyanna Dayne of Starfall, who bore him a brood of children: his sons Daeron, Aerion Brightflame, Aemon, and Aegon, and daughters besides.
Maekar made his name as a warrior. He commanded a wing of the loyalist host at the Battle of the Redgrass Field in the First Blackfyre Rebellion, and in 209 AC he fought in the Trial of Seven at Ashford, where it was his own mace that struck down his brother Baelor Breakspear, a blow that killed the beloved prince within days and weighed on Maekar's conscience ever after. It was in Maekar's service that the hedge knight Ser Duncan the Tall took a place, and Maekar's youngest son Aegon, called Egg, who rode the roads of Westeros as Dunk's squire. Though plagued by jealousy and a hard pride, Maekar was no fool, and he understood the work of rule better than his bookish brother Aerys.
When Aerys I died childless in 221 AC, with their brother Rhaegel and Rhaegel's children also dead, the crown passed at last to Maekar, the only son of Daeron the Good still living. He kept his nephew Brynden Rivers, called Bloodraven, as Hand of the King, grudgingly accepting the man whose long success under Aerys he could not deny. Maekar reigned twelve years, until in 233 AC he met his death beneath the walls of a rebellious lord's castle, struck down as he led the assault. His passing left a tangled succession, for his eldest sons Daeron and Aerion were already dead and his son Aemon had taken a maester's vows, and so Bloodraven called a Great Council to King's Landing, which set aside the claims of his grandsons and raised his youngest son to the throne as Aegon V.