Known by the nickname “Good King,” it’s pretty obvious that Jaehaerys was one of the most popular kings in the history of the Seven Kingdoms. Though his fellow beloved king Aegon the Conqueror was known as a fierce warrior and was the first King of the Seven Kingdoms to boot — and the start of the royal Targaryen dynasty — Jaehaerys held an important record as the longest monarch in the history of the realm.
Jaehaerys ruled the Seven Kingdoms for, according to George R.R. Martin’s source material “Fire and Blood,” a whopping fifty five years, and by all accounts, they were pretty uniformly good ones as well. (He’s also, kind of rudely, referred to as “The Old King.”) Jaehaerys’ legacy is also pretty storied; he’s credited with keeping the realm peaceful and prosperous, and he also was able to forge truces between warring houses to keep things level, including one between House Bracken and House Blackwood, two houses of the Riverlands.
In his youth, Jaehaerys was also a formidable fighter, facing off personally against Dornish forces during a skirmish known as the Third Dornish War, and in the early days of his reign, he more or less created a system of laws that would govern the realm for centuries to come. Finally, he was also famous as a dragon-rider; he rode Vermithor, who was the third-largest dragon in Westerosi history behind Balerion — whose skull resides in the crypts of King’s Landing — and Vhagar, whose whereabouts are unknown during the events of “House of the Dragon.”