Gylen Hightower was the Lord of Oldtown, Lord Paramount of the Reach, and Warden of the South. In the fourth era, before his death, he declared himself King of the Reach. He has one son, Gerold Hightower.
Gylen Hightower was the third son of Old Garth Hightower and Lady Enora Beesbury. He had two older brothers, Gavyn and Young Garth, and a younger sister, Gera Hightower. As a child, Gylen was indoctrinated into his father's fanatic, patriotic set of ideals. He was trained to hate the Tyrells for all they stood for, with little reason besides a belief that the Hightowers of Oldtown were the true masters of the Reach. Gylen carried these beliefs fervently throughout his youth without question.
Old Garth organized his sons lessons in a diabolically clever way. Firstborn 'Young' Garth was trained in the ways of combat and fighting. Next in line was Gavyn, who was trained as a military commander. Lastly, Gylen received lessons in lording and politics. All three became proficient in their skills, but only those skills. All three would support each other, but Gylen was the safety. As third in line, he would always be there to pull the strings.
Old Garth died when Gylen was ten-and-six. The lord had gone delusional in his last days, spouting madness and obscenities. Oldtown did not have long to grieve. Soon after, the Second Greyjoy Rebellion began and the lords of Westeros traveled to the Iron Islands for another spree of justice and killing. The two older brothers left for Blacktyde, but only one returned. Gavyn was swiftly killed in battle, and in his attempt to save him, Young Garth was injured and fully paralyzed.
The people of Oldtown grieved more at the news. Two Hightowers were dead now, and the last was doomed to live the life of a cripple. However, that cripple was their lord now, and the people worried for the sake of Oldtown. No one worried more than Gylen. The stories say Young Garth valiantly sacrificed himself to pass the reigns of lordship to his more capable brother. The details of what happened in the Hightower the day Young Garth died are unknown, but Gylen was eager to take command as the Voice of Oldtown.
Gylen purchased the Golden Company and attended the Council at Bloodstone where he expressed support of a Blackfyre throne. When he kidnapped Maude Tyrell from the Red Keep, King Harys Baratheon marched his army to Oldtown, giving the Lannisters the opening needed to take the capital for Aerion Blackfyre.
Troy Tyrell broke the guest right at Oldtown by laying hands on Gylen, prompting him to demand that the King and his men leave. He remained in Oldtown, but sent some of the Golden Company to serve the Lannisters in holding the throne.
When King Harys marched on King's Landing, Gylen used the remainder of the company to sack Highgarden and burn it to the ground. King Damon Lannister recognized him as the new Lord Paramount of the Reach, and agreed to bestow the remains of the former seat to Robert Manderly at Gylen's behest.
Gylen converted to the faith of Rh'llor, though practiced in secret. He agreed to a marriage pact with the King and wed his eldest son, Gerold, to Ashara Lannister. He accepted a position as an advisor to the small council. Gerold and Ashara remained at Oldtown and presided over the Reach while Gylen was in King's Landing.
As advisor on the Small Council, Gylen slowly grew opposed to his King, and especially his new Queen, Danae Targaryen. At the Maiden's Day Festival, Gylen discovered Baelor Tyrell's baseborn son, Aurane Flowers, plotting with Meredyth Tyrell. Aurane was given a controversial trial by combat, in which a pit of fire was lit beneath Flowers and his foe. Aurane escaped, and Gylen drew unwanted attention to himself.
After a Reach lord was caught trespassing in Dorne, the relations between the two kingdoms soured. A controversial decision from Eon Crakehall regarding the matter left Dorne and its Princess feeling slighted.
Tensions between the King and Gylen reached new heights in the third era. After the Queen fled to Dragonstone, Gylen renounced his loyalty and declared the Reach an independent kingdom.
The newly declared King Gylen named Lord Ferment Redwyne as his Hand and the Arbor's fleet set sail, defeating Aemon Estermont and the royal fleet in the Battle for the Straits, the first conflict in the War of the False King.
While winning the battle for the straits, Gylen suffered a critical loss at the Shield Islands where the Ironborn fleet won a decisive victory, burning and raising the keeps before moving on up the Mander and capturing Highgarden.
The war cumulated in a final conflict at Old Town. With the ironborn fleet blockading the harbor and the King's forces on his doorstep, Gylen burned and hung Mellara Tyrell from the ramparts of the Hightower, meaning to fool Damon into believing it was his sister Ashara Lannister.
Danae Targaryen arrived on the back of her dragon during the siege and burned the Redwyne fleet in the harbor. Gylen, believing the war to be lost, brought Ashara to the top of the Hightower, intent on sacrificing her to the flame. However, before he could do so, Danae and her dragon landed on the top of the tower, and after a tense standoff Gylen was roasted alive by Persion, setting the top of the Hightower alight in flame.
"A shrewd man, and a master strategist… [Gylen is] proud and violent... Could be he's a little mad, but he's very effective." - Damon Lannister
"Damon already knows I don't like this plan. Or the Dragon. Or his wife. And how he mistrusts me for it, for being the only honest advisor on his fucking council." - Gylen Hightower
Old Garth Hightower, father (deceased)
Enora Beesbury, mother (deceased)
Gavyn, brother (deceased)
Young Garth, brother (deceased)
Gera Hightower, sister
Gerold Hightower, son