Possible Clues:

• First of 13 popes
• Sainted fifth-century pope
• Sainted pope called "the Great"
• Fifth-century pope
• Sainted pope called 'the Great'
• Pope from 440 to 461
• Fifth-century pope known as 'the Great'
• Fifth-century pope known as ''the Great''
• Fifth-century pope called 'the Great'
• First pope called 'the Great'