Ser Raymund Frey is the eleventh son of Walder Frey and the sixth from his marriage to Amarei Crakehall. He is married to Beony Beesbury and has seven children, Robert, Malwyn, Sarra, Serra, Cersei, Tywin, and Jaime Frey.
During the Red Wedding Jon Umber "the Smalljon" bludgeons Ser Raymund Frey across the face with a leg of mutton, but is then killed by Northmen under the command of Roose Bolton. Raymund Frey cuts Catelyn's throat after she kills his half-nephew Aegon "Jinglebell" Frey. The Freys had intended to keep her as a hostage, but seeing her son Robb Stark murdered in front of her by Lord Bolton drove her insane. The Freys strip Catelyn and throw her into the river, in a mockery of Tully funeral customs. This backfires when Catelyn is resurrected by Beric Dondarrion at the cost of his life, becoming Lady Stoneheart and determined to gain vengeance on those responsible for the death of her family, including the Freys.
- In the HBO series, Raymund;s role in murdering Catelyn was taken by "Black Walder Rivers", a merging of Walder Frey's great-grandson Black Walder Frey and bastard Walder Rivers.