Sadyrnfyw, also known as Sadwrnfen the Generous, was a medieval Welsh bishop who served at Meneva, which is known today as St. David's. Born around 750, he held his ecclesiastical position during the 8th and 9th centuries. Historical records regarding his passing vary slightly, with the Chronicle of the Princes suggesting he died in 830, while other reconstructions of the Annals of Wales place his death in approximately 831. He is recognized as a saint within certain Christian traditions.