Kaeth was a maester of the Citadel. Circa 257 AL 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 served for less than a year before dying. He was succeeded by Ellendore.
Kaeth is well-regarded for his work, Lives of Four Kings, a detailed history of the reigns of Kings Daeron I, Baelor the Blessed, Aegon IV Targaryen and Daeron II. 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.
Kaeth was the first of three Grand Maesters to die in less than two years, which eventually encouraged the Citadel to elect Pycelle to the post at the surprisingly young age of forty-two.