The Red Book of Hergest (Welsh: Llyfr Coch Hergest, Oxford, Jesus College, MS 111) is a large vellum manuscript written shortly after 1382, which ranks as one of the most important medieval manuscripts written in the Welsh language. It preserves a collection of Welsh prose and poetry, notably the tales of the Mabinogion and Gogynfeirdd poetry. The manuscript derives its name from the colour of its leather binding and from its association with Hergest Court between the late 15th and early 17th century.