Qyburn

Qyburn is a recurring character from A Song of Ice and Fire.

In the adaptation TV series, he is portrayed by Anton Lesser.

Qyburn was a former maester of the Citadel, stripped of his chain by the Archmaesters after practicing forbidden and unethical experiments.

History
Qyburn studied at the citadel and was as skilled a healer as Maester Ebrose. Qyburn sought to surpass him though and instead of opening the bodies of the dead to discover the secrets of the living as the citadel has done for centuries, Qyburn instead opened the bodies of the still living to discover the secrets of death. When this was discovered, Qyburn was stripped from his position as a maester for unethical experiments he performed on living humans.

Qyburn joined the Brave Companions as a means to survive. Qyburn only had respect for Archmaester Marwyn of the Citadel, calling other archmaesters the "grey sheep".

Game of Thrones
Qyburn was held captive at Harrenhal by Ser Gregor Clegane, until the latter abandons the castle and has all the captives killed. Qyburn survives and stays at Harrenhal with Lord Roose Bolton. Later he reaches King's Landing along with Brienne of Tarth and Ser Jaime Lannister.

He starts to ingratiate himself with Queen Regent Cersei Lannister and tries to save Ser Gregor from death after the fight against Prince Oberyn Martell.

A Clash of Kings
When the Brave Companions turn cloak and take Harrenhal for Lord Roose Bolton, Qyburn takes over the duties of Harrenhal's maester Tothmure, who is killed for dispatching ravens to King's Landing. It is mentioned by Gendry that Qyburn is rumored to have knowledge of black magic and necromancy.

A Storm of Swords
When Ser Jaime Lannister is captured and brought to Harrenhal, Roose orders Jaime to be brought to Qyburn. He uses his exceptional healing abilities to prevent the infection on Jaime's severed wrist from spreading. He accompanies Jaime to King's Landing when Roose decided to send him back to his father, Lord Tywin Lannister. Before departing Qyburn sends Jaime Pia hoping to ingratiate himself with the Lannisters; Jaime, however, sends the girl away.

A Feast for Crows
Qyburn leaves the company and joins the court at King's Landing, where he convinces Queen Cersei Lannister to allow him to experiment on the dying Ser Gregor Clegane. He later gains favor with her by using his knowledge to torture her prisoners. Cersei eventually appoints him as master of whisperers to replace Varys after his disappearance. Qyburn also took Varys's place on the small council.

Part of the payment for Qyburn's services to Cersei includes permission to experiment on various prisoners and enemies of Cersei's. These typically prove fatal to the subject. Qyburn works on a master project to build an "undefeatable champion" for Cersei. He orders a massive suit of armor, too huge to be worn by any human, for this purpose. His extended experiments on Gregor Clegane seem to factor into the size of his creation. Qyburn may also have some knowledge of magic, as he suspects Prince Oberyn Martell to have used it on his venom to prolong Clegane's death.

A Dance with Dragons
Qyburn is present at the Red Keep when Cersei completes her penance walk and introduces Cersei to her champion and the newest member of the Kingsguard, Ser Robert Strong. Qyburn, though dismissed from the small council, still works with the eunuch's whisperers. According to Ser Kevan Lannister, Qyburn is in charge of the dungeons where most of the (falsely) accused lovers of Margaery Tyrell are held. Cersei is delighted to hear this, as Qyburn was the one last straw she could clutch in King's Landing.