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Pope Leo

Pope Leo is the regnal name used by fourteen popes of the Catholic Church, from Leo I in the 5th century to Leo XIV, elected in 2025.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

Pope Leo is the regnal name used by fourteen popes of the Catholic Church, from Leo I in the 5th century to Leo XIV, elected in 2025. The name is especially associated with Leo I “the Great,” Leo X of the Renaissance, and Leo XIII, known for his social teaching.

List of popes named Leo

The name Leo has been used by fourteen popes across the history of the Catholic Church, beginning with Leo I and continuing most recently with Leo XIV. The list includes several saints and major historical figures.

Pope Leo I

Leo I, also known as Leo the Great, served as bishop of Rome from 440 until his death in 461. He is remembered for strengthening papal authority and for his role in Christological debates, especially at the Council of Chalcedon.

Pope Leo X

Leo X was pope from 1513 to 1521 and belonged to the Medici family. His pontificate is associated with the early Reformation, including his conflict with Martin Luther.

Pope Leo XIII

Leo XIII was pope from 1878 to 1903. He is especially known for *Rerum Novarum* (1891), a major encyclical on workers’ rights and social conditions.

Key facts

  • Pope Leo is a papal regnal name, not a single person.
  • Fourteen popes have used the name Leo.
  • Leo I reigned from 440 to 461 and was later called “the Great.”
  • Leo X reigned from 1513 to 1521 and is closely linked to the early Protestant Reformation.
  • Leo XIII reigned from 1878 to 1903 and is known for the encyclical *Rerum Novarum*.
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Canadian context

Canadian Catholics and historians may encounter the name Leo most often in discussions of papal history, Catholic social teaching, and the Reformation; Leo XIII’s *Rerum Novarum* especially influenced Catholic social thought in Canada.

Frequently asked questions

Who was Pope Leo?
“Pope Leo” refers to any of fourteen popes who took the name Leo, not one individual. The first was Leo I in 440, and the most recent was Leo XIV, elected in 2025.
Pope Leo X
Leo X was pope from 1513 to 1521. He was a Medici and is often remembered for his role during the early Protestant Reformation.
Pope Leo XIII
Leo XIII was pope from 1878 to 1903. He is best known for *Rerum Novarum*, an encyclical that became foundational in modern Catholic social teaching.
Pope Leo encyclical
The best-known encyclical by Pope Leo XIII is *Rerum Novarum* (1891), which addressed labour, wages, and the rights and duties of workers and employers.
Pope Leo and Luther
Pope Leo X was pope during Martin Luther’s break with Rome. Leo X condemned Luther’s teachings and issued the bull *Exsurge Domine* in 1520, followed by excommunication.
Pope Leo death
Pope Leo I died on 10 November 461 in Rome. Pope Leo X died on 1 December 1521, and Pope Leo XIII died on 20 July 1903.

References

  1. Wikipedia — https://en.wikipedia.org/wiki/Pope_Leo
    Supports: List of popes named Leo and numbering through Leo XIV.
  2. Wikipedia — https://en.wikipedia.org/wiki/Pope_Leo_I
    Supports: Leo I dates, title 'the Great,' and papacy dates.
  3. Encyclopaedia Britannica — https://www.britannica.com/biography/Saint-Leo-I
    Supports: Leo I as pope from 440 to 461 and historical significance.
  4. Vatican News — https://www.vaticannews.va/en/saints/11/10/st--leo-the-great--pope-and-doctor-of-the-church.html
    Supports: Leo I as first pope named Leo, doctor of the Church, and burial in St. Peter's Basilica.
  5. Wikipedia — https://en.wikipedia.org/wiki/Pope_Leo_X
    Supports: Leo X dates, Medici identity, and death date.
  6. Wikipedia — https://en.wikipedia.org/wiki/Pope_Leo_XIII
    Supports: Leo XIII dates and papacy.
  7. Britannica Kids — https://kids.britannica.com/students/article/Leo-popes/275433
    Supports: Leo X as pope during the Reformation and connection to Luther.
  8. National Geographic — https://www.nationalgeographic.com/history/article/pope-name-pontiff-leo-meaning
    Supports: Leo I, Leo X and Leo XIII historical significance; Luther excommunication context.