Why did the Pope pick Leo? Here’s why the name is so important in the Catholic Church

Pope Leo I tangled with Attila the Hun and won. Pope Leo III crowned Charlemagne as the first Holy Roman Emperor. This is the history of a legendary papal namesake.

A mans hands are clasped with, while looking outward on a black background.
Cardinal Robert Francis Prevost chose a name steeped in hundreds of years of religious tradition after his election as pope: Pope Leo XIV. 
Photograph By Evandro Inetti/ZUMA Press /Alamy
ByMelissa Sartore
Last updated August 25, 2025

Cardinal Robert Francis Prevost made history by becoming the first Roman Catholic pope from North America. Once elected, however, he chose a pontifical name steeped in hundreds of years of religious tradition: Pope Leo XIV. 

"While there are no strict rules governing how popes choose their papal names, the selections are made deliberately and are usually taken to have significance in relation to previous popes of the same name," says Karl Shoemaker, a history professor at University of Wisconsin-Madison with affiliate appointments in religious studies, legal studies, and sociology.

As the number indicates, Prevost is the 14th pope with the name Leo. In his address to the College of Cardinals on May 10, Pope Leo XIV explained that he had "different reasons" for choosing the name but he was mainly inspired by the most recent of his namesakes—Pope Leo XIII, who spent much of his papacy advocating for the rights of workers during the first industrial revolution.

The significance of the name is clear when looking at the pontificates of his predecessors. From Pope Leo I and his purported exchange with Attila the Hun to Pope Leo IX's role in the Great Schism of A.D. 1054, the pontifical name holds great importance within the Roman Catholic Church. 

(The first U.S. pope? Rome reacts to a once impossible scenario.)

A sculpture of a a man in a robe sitting on a chair with a large hat.
The last pope to take the name Leo was Pope Leo XIII. Born Vincenzo Gioacchino Raffaele Luigi Pecci, he was elected pope on February 20, 1878, and reigned until his death in 1903. He is known as a pope of the working class. His marble likeness seen here is on display at Catholic University in Washington, D.C.
Photograph By ARCHIVIO GBB / CONTRASTO/Redux

Who was the first Pope Leo?

The name Leo means "lion" in Latin and carries with it a sense of regality, dignity, and leadership. Pope Leo I, the first of three popes in all of history who earned the title "the Great," embodies all of these characteristics within Roman Catholicism. 

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Leo I became pope on September 29, A.D. 440, a formative time for the Church. As Catholicism spread and hammered out doctrine, new ideas and questions about details were quick to develop—leading to the rise of heretical groups. Pope Leo I immediately sought to eliminate these heretics and communicated with bishops across the Roman Empire to emphasize unity. He also oversaw the ecumenical council at Chalcedon in A.D. 451, which is where the Roman Catholic Church affirmed the dual nature of Christ as divine and human. 

A colorful illustration of a man looking down on a roman soldier while holding a staff.
Pope Leo I set a high bar for all future popes who would take his name. During his papacy from A.D. 440 to A.D. 461, he solidified the doctrine of the Roman Catholic Church and legend has it that he even persuaded Attila the Hun to spare Rome from invasion.
Illustration by Cibera, Photograph byTarker /Bridgeman

Alongside his role in solidifying church doctrine, legend has it that Pope Leo I came face to face with Attila the Hun in A.D. 452—and won. Attila had crossed into Italy with his coalition of Goths, Huns, and others seeking to conquer and pillage Europe. But medieval texts suggest that he spared Rome after Leo appealed to him directly. 

(Who were the ruthless warriors behind Attila the Hun?)

Pope Leo I also has the rare distinction of being named a Doctor of the Church after his death in A.D. 461. This designation is reserved for saints whose writings hold special authority within the Church. As recently as 2008, Pope Benedict XVI discussed Leo the Great, explaining "As the nickname soon attributed to him by tradition suggests, he was truly one of the greatest Pontiffs to have honoured the Roman See and made a very important contribution to strengthening its authority and prestige."

A n alter piece made of marble.
Medieval texts claim that Pope Leo I went to meet with Attila the Hun after the conqueror's forces crossed into Italy to plead for mercy on behalf of Rome—a scene depicted here on this marble relief. One text recounts that Attila "straightway promised a lasting peace and withdrew beyond the Danube."
Photograph By NPL - DeA Picture Library / G. Cigolini / Bridgeman Images

Leo III and the first Holy Roman Emperor

Pope Leo III was another pontiff who led during a formative time in Roman Catholicism. Elected in A.D. 795, Pope Leo III was the pope who crowned Charlemagne as the first Holy Roman emperor. 

“Many historians credit Charlemagne with spreading Christianity across these formerly pagan regions, bringing a common culture and homogeneity to disparate tribes,” according to National Geographic’s Inside the Medieval World. The ruler became defender of the Christian faith and, under him, the continent flourished.

Pope Leo III’s decision to name the emperor as leader of the Church  reaffirmed the relationship between the papacy and the Frankish rulers who would protect the Catholic Church against threats to its land and rights. It also set the stage for actions taken by Pope Leo IX centuries later—when issues of authority and doctrine split Christendom in two.

An illustration of a man with robes and a large hat.
Elected in A.D. 795, Pope Leo III was the pope who crowned Charlemagne as the first Holy Roman emperor—setting the stage for a Great Schism that would come under one of his namesake successors.
Photograph By Tarker / Bridgeman Images

Pope Leo IX and the Great Schism

Born Bruno of Egisheim, Pope Leo IX became the leader of the Catholic Church and ruler of the Papal States, the territory in and around Rome, in A.D. 1049. 

At the time, the relationship between Rome and Constantinople was strained. After Emperor Constantine had shifted the authority of the Roman Empire east to Constantinople in A.D. 330, the city increased in power and prominence over the centuries that followed—ultimately becoming the "New Rome." The Patriarch of Constantinople considered himself equal to the bishop of Rome and, as a result, there was tension over where primacy in Catholicism was truly based. 

(Istanbul’s ancient imperial legacy lies hidden in plain sight.)

Catholics on both ends of the Mediterranean had adopted disparate practices (the use of unleavened or leavened bread, for example) and several doctrinal details between the two traditions remained unresolved. Cultural differences further exacerbated the conflict, especially language as the west remained devoted to Latin Mass and the east adopted Greek.

Leo IX, head-and-shoulders portrait, facing left.
A photo of a statue taken from below the figure is holding a long staff and has a large hat.
Born Bruno of Egisheim, Pope Leo IX told hold of the Holy See at a time when the eastern and western sects of the Catholic Church were deeply divided. One of his final acts ultimately led to what is known as the Great Schism of A.D. 1054 that split the church into the Roman Catholic Church and the Eastern Orthodox Church.
Print By J. William Gnecchi, Libarary of Congress (Top) (Left) and Photograph By Azoor Photo Collection / Alamy (Bottom) (Right)

Things came to a head after Constantinople closed all its Latin churches. In response, Pope Leo IX sent a delegation led by Hubert of Silva Candida to Constantinople ostensibly to settle the disagreement with Patriarch Michael Cerularius. Instead, Hubert placed an excommunication bull for the patriarch in the city on the altar at Hagia Sophia on July 16, 1054 A.D.

Pope Leo IX had died by the time of the excommunication, but it was nonetheless a move that he had initiated. As a result, the Roman Catholic Church based in Rome and the Eastern Orthodox Church centered in Constantinople became two separate entities after this Great Schism.

Pope Leo X excommunicates Martin Luther

Another Pope Leo—Pope Leo X—also faced a divisive moment within Christendom. Pope Leo X (born Giovanni di Lorenzo de' Medici) held the papal see from 1513 to 1521 A.D. During the last year of his pontificate, Pope Leo X excommunicated Martin Luther. 

A black and while print of a man with aa round head and figure.
Pope Leo X—whose papacy lasted from A.D. 1513 to 1521—oversaw another controversial time in the Catholic Church. He is the pope who excommunicated Martin Luther, leader of the Protestant Reformation, which ultimately once again splintered the faith.
Print by Lucas Vorsterman I, Peter Paul Rubens/The Metropolitan Museum of Art

Luther, a German theologian and former Augustinian friar, had become a vocal critic of the Catholic Church. In A.D. 1517, he famously articulated accusations of corruption against the Church and asserted that salvation came through faith rather than good works and indulgences in his Ninety-five Theses. By A.D. 1521, Luther's refusal to recant his claims at the Diet of Worms led to Pope Leo X issuing a bull of excommunication for Luther and his followers.

Martin Luther was one of the key figures in the Protestant Reformation of the 16th century in which western Christianity was split in two—with the Roman Catholic Church in one camp and Protestant faiths like Lutheranism in the other. 

(How Martin Luther started a religious revolution.)

Popes Leo and the spirit of unity

Collectively, these popes are among the most influential men to hold the pontifical seat. They advocated for unity and devotion alike.

This held true for Pope Leo XIII, who held the Holy See from 1878 to 1903. An intellectual who acknowledged the need for science, modern ideas, and open mindedness, Pope Leo XIII was very much a theologian too. As the Pope Leo XIII Institute put it, he saw "deeply into the reality of the world, always acutely aware of the invisible yet very real battle being waged against the soul of each person and against communities everywhere."

A man sits on a chair in a white robe and hat waves at the camera.
According to Reuters, Pope Leo XIII spent much of his papacy "on advocating for the rights of workers, calling for fair pay, fair working conditions, and the right to join unions"—leaving many wondering whether his successor, Pope Leo XIV, will do the same.
Photograph By Library of Congress

This spirit was captured by Pope Leo XIV in his initial remarks to the world. His statement about working together to build bridges, communicate, and be "open to all, to all who need our charity, our presence, dialogue, and love" echoes Pope Leo XIII with a sense of hope for the future.

And in his subsequent address to the College of Cardinals, Pope Leo XIV explained that he was inspired by Pope Leo XIII and his teachings on the rights or workers amid the first industrial revolution—which he compared the modern rise of artificial intelligence.

"In our own day," Pope Leo XIV said, "the Church offers to everyone the treasury of her social teaching in response to another industrial revolution and to developments in the field of artificial intelligence that pose new challenges for the defense of human dignity, justice, and labor."

Editor's note: This story originally misstated when Martin Luther published his 95 Theses and whether he attended the Diet of Worms. It also misstated the dates of Leo X's papal reign. It has been corrected.