Kaeth was a maester of the Citadel. About 257AL he was made Grand Maester at the age of eighty and sent to serve the court of King Aegon V Targaryen in King’s Landing. He died within a year of his appointment and was succeeded by Grand Maester Ellendor.

Grand Maester Kaeth wrote the well-regarded work Lives of Four Kings, a detailed history history of the reigns of Daeron the Young Dragon, Baelor the Blessed, Aegon the Unworthy, and Daeron the Good. Kaeth scants Viserys II terribly, however, as his short reign as king came after Baelor’s. The book is considered to be an excellent treatise of the art of rulership. Ser Kevan Lannister and his nephew Tyrion are amongst its appreciators, as was Prince Oberyn Martell.