Saint Leo the Great (c. 400-461) was Pope and Doctor of the Church whose Tome clarified the Catholic faith in the two natures of Christ at the Council of Chalcedon in 451. He famously persuaded Attila the Hun to spare Rome and strengthened the authority and unity of the Church. He is one of only a few popes called 'the Great.'

November 10

• the papacy
• against heresy

Canonized

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