Aegon II Targaryen, King of the Seven Kingdoms

From Asoiaf

Aegon II of House Targaryen, King of the Seven Kingdoms (reigned 129 AL - 131 AL), was the oldest son of Viserys I Targaryen, King of the Seven Kingdoms.

Aegon's ascent on his father's death was disputed by his older sister Rhaenyra. Both perished in the following war, called the Dance of Dragons. Rhaenyra's son Aegon III then became king.