Orys I's brother

"Orys the First was just. Everyone applauded his reforms. Nobles and commoners alike. But he wasn't just for long. He was murdered in his sleep after less than a year by his own brother. Was that truly just of him? To abandon his subjects to an evil that he was too gullible to recognize?"

- Tywin Lannister to Tommen Baratheon This individual was the brother of Orys I, a king who ruled in Westeros at some time prior to the War of the Five Kings. Despite the reforms introduced by Orys, which were applauded by both commoners and nobles alike, this individual murdered his brother while he slept after less than a year. This action would come to damage the prosperity and safety of Orys' kingdom.

Season 4
Tywin Lannister mentions this individual's actions to his grandson, King Tommen Baratheon, as an anecdote to help Tommen learn to be king, after the death of Tommen's own brother Joffrey.