A regent is in charge of ruling a realm when a king or lord is underage or incapable of ruling due to injury or illness. The regent's service ends on the ruler's sixteenth name day or when the ruler recovers from his injury. Royal regents have also taken the title "Protector of the Realm", a title usually reserved for the king.
During the infancy of Lady Jeyne Arryn, Lord Yorbert Royce served as her regent and Lord Protector of the Eyrie and the Vale of Arryn. In that capacity, he attended the Great Council of 101 in her stead.
After Lord Rickon Stark died in 121 AC, his brother Bennard served as regent for Lord Cregan Stark, until his coming of age in 124 AC. Bennard was slow to surrender his power to his nephew, and Cregan chafed at the limits imposed on him. In 126 AC, Lord Cregan rose up against his uncle, imprisoned Bennard and his sons, and took the rule of the north into his own hands.
Prince Aemond Targaryen became Prince Regent after his brother, King Aegon II Targaryen, was severely wounded and incapacitated for a year after the battle at Rook's Rest during the Dance of the Dragons. The mother of young Lord Lyonel Tyrell was regent for the Reach at the start of the civil war.
A Game of Thrones
In the will of King Robert I Baratheon, Lord Eddard Stark is named Lord Regent to Joffrey I Baratheon, but his regency never transpires. Robert's widow, Cersei Lannister, declares herself Queen Regent to Joffrey after Eddard is arrested.
A Clash of Kings
A Feast for Crows
Cersei continues serving as Queen Regent for the new king, Tommen I Baratheon, after the deaths of Joffrey and Tywin and the flight from the capital by Tyrion. Ser Kevan Lannister rejects the office of Hand of the King when Cersei refuses to make him Regent.
The death of Lysa Arryn leads to her second husband, Lord Petyr Baelish, consolidating his role as regent for his step-son Robert Arryn in his role as Lord Protector of the Eyrie and the Vale of Arryn.
A Dance with Dragons
- The World of Ice & Fire, The Reach: Oldtown.
- The World of Ice & Fire, The Reach: House Tyrell.
- The World of Ice & Fire, The Reign of the Dragons: The Conquest.
- The World of Ice & Fire, The Targaryen Kings: Jaehaerys I.
- Fire & Blood, Heirs of the Dragon – A Question of Succession.
- Fire & Blood, A Son for a Son.
- The Princess and the Queen.
- The World of Ice & Fire, The Targaryen Kings: Aegon III.
- The World of Ice & Fire, The Westerlands: House Lannister under the Dragons.
- A Feast for Crows, Chapter 23, Alayne I.
- A Game of Thrones, Chapter 47, Eddard XIII.
- A Game of Thrones, Chapter 57, Sansa V.
- A Clash of Kings, Chapter 3, Tyrion I.
- A Feast for Crows, Chapter 3, Cersei I.
- A Dance with Dragons, Chapter 54, Cersei I.