Illtud, also known as Illtud Farchog or Illtud the Knight, is venerated as the abbot teacher of the divinity school, Bangor Illtyd, located in Llanilltud Fawr in Glamorgan, Wales. He founded the monastery and college in the 6th century, and the school is believed to be Britain's earliest centre of learning. At its height, it had over a thousand pupils and schooled many of the great saints of the age, such as David, Samson of Dol, and the historian Gildas.

St Illtyd's Church is a church complex in Llantwit Major, Vale of Glamorgan, southeast Wales. It is located at the site of the oldest college in the United Kingdom, once believed to have been founded as Côr Tewdws c. AD 395 by the Roman Emperor Theodosius II. It is now generally accepted as having been founded by St. Illtud c. AD 508, from whom it derives its name. The current church building was built in the 11th century by the Normans, with portions being rebuilt in the 13th and 15th centuries. The church building is one of the oldest and best-known parish churches in Wales. It is a grade I listed building, or building of exceptional interest, and has been called both the "Westminster Abbey of Wales" for its unique collection of carved stones and effigies, and "the most beautiful church in Wales."