Isabella of Portugal (1503 - 1539)

Habsburg Queen, Queen and Regent of Spain

Isabella of Portugal (1503-1539). Engraving. Colored.
Corbis via Getty Images / Getty Images

Isabella of Portugal Facts

Known for: regent of Spain during long absences of her husband, Charles V, Holy Roman Emperor
Titles: Empress, Holy Roman Empire; Queen of Germany, Spain, Naples, and Sicily; Duchess of Burgundy; princess (Infanta) of Portugal
Dates: October 24, 1503 - May 1, 1539

Background, Family:

Mother: Maria of Castile and Aragon

  • Maternal grandparents: Isabella I of Castile and Ferdinand II of Aragon.
  • Maria was the second wife of Manuel I
  • Manuel's first wife, Isabella, Princess of Asturias, was Maria's sister, the eldest daughter of Isabella I and Ferdinand II
  • Manuel's third wife, Eleanor of Austria, was a niece of both Maria and Isabella, Manuel's wives

Father: Manuel I of Portugal

  • Paternal grandfather: Ferdinand, Duke of Viseu
  • Paternal grandmother: Beatrice of Portugal
  • Beatrice was a sister-in-law and first cousin of Afonso V of Portugal, and mother-in-law and second cousin of John II of Portugal
  • Beatrice's sister, also called Isabella of Portugal, married John II of Castile, and was the mother of Isabella I
  • Manuel succeeded his first cousin, John II of Portugal, who was married to Manuel's sister, Eleanor of Viseu
  • Manuel's older brother, Diogo, was stabbed to death by John II

Siblings of Isabella of Portugal:

  • Miguel de Paz, Prince of Portugal and Asturias
  • John III of Portugal
  • Beatrice, Duchess of Savoy
  • Louis
  • Ferdinand
  • Cardinal Afonso
  • Henry
  • Edward
  • Maria, Duchess of Viseau

Marriage, Children:

Husband: Charles V, Holy Roman Emperor (married March 11, 1526)

  • Charles was Isabella's first cousin
  • his father was Philip the Handsome, Duke of Burgundy and Holy Roman Emperor
  • his mother was Joanna of Castile (known as Juana the Mad), a sister of Isabella's mother, Maria, both daughters of Isabella I and Ferdinand II
  • Isabella's brother, John III of Portugal, had earlier married Catherine of Austria, sister of Charles V, in 1525


  • Philip II of Spain (1527 - 1598), who married four times: Maria Manuela of Portugal, Mary I of England, Elizabeth of France, and Anna of Austria
  • Maria (1528 - 1603), Holy Roman Empress, married to Maximilian II, her first cousin
  • Joan of Austria (1535 - 1573), who married her double first cousin, John (João Manuel) of Portugal; their child was King Sebastian of Portugal, who died without children
  • Three children who were stillborn or died in infancy: Ferdinand (1529 - 1530), John (1537 - 1538), and an unnamed son (1539)

Isabella of Portugal Biography:

Isabella was born the second of the children of Manuel I of Portugal and his second wife, Maria of Castile and Aragon. She was born in a year of sharp decline in her grandmother, Isabella I of Castile, who died the next year.


When her father died in 1521, her brother, John III of Portugal, negotiated a marriage with Catherine of Austria, sister of Charles V, the Holy Roman Emperor. That marriage took place in 1525, by which time negotiations had arranged for Charles to marry Isabella. They were married on March 10, 1526, at the Alcázar, a Moorish palace.

John III and Isabella, brother and sister, were first cousins of the sister and brother they married: they were all grandchildren of Isabella I of Castile and Ferdinand of Aragon, whose marriage united Spain.

Isabella and Charles may have married for financial and dynastic reasons -- she brought a large dowry to Spain -- but letters of the time show that their relationship was more than just a marriage of convenience.

Charles V is known for creating a world empire, molding a great Habsburg empire which was rooted in Spain rather than in Germany. Before his marriage to Isabella, other marriages had been explored for him, including marrying a daughter of Louis XII and a sister, Mary Tudor, of Henry VIII of England, a Hungarian princess. Mary Tudor married the King of France, but after she was widowed, talks had begun to marry her to Charles V. When the alliance of Henry VIII and Charles V fell apart, and Charles was still in conflict with France, the marriage with Isabella of Portugal was the logical choice.

Isabella has been described as frail and delicate from the time of her marriage. They shared religious piety. 

Children and Legacy

During Charles' absences from Spain in 1529-1532 and 1535-1539, Isabella served as his regent. They had six children, of whom the first, third and fifth survived to adulthood.

During one of Charles' absences, Isabella died after giving birth to her sixth child, a stillbirth. She was buried at Granada.

Charles did not remarry, though that was the usual custom for rulers. He wore mourning black until his death. He later built a royal tomb, where the remains of Charles V and Isabella of Portugal are together with those of Charles' mother, Juana, two of his sisters, two of their children who died in infancy, and a daughter-in-law.

Isabella and Charles' son Philip II became ruler of Spain, and in 1580, also became the ruler of Portugal. This temporarily united the two Iberian countries.

A portrait of Empress Isabella by Titian portrays her at her needlework, presumably waiting for the return of her husband.

Joan of Austria and Sebastian of Portugal

This daughter of Isabella of Portugal was the mother of the ill-fated Sebastian of Portugal and ruled Spain as regent for her brother Philip II.

Known for: Habsburg princess; regent of Spain for her brother, Philip II

Title by marriage: Princess of Portugal
Dates: June 24, 1535 - September 7, 1573
Also known as: Joan of Spain, Joanna, doña Juana, Dona Joana

Marriage, Children:

  • husband: Infante John Manuel, Prince of Portugal (married 1552)
  • one child:
  • Sebastian of Portugal (1554 - 1578)

Joan of Austria Biography:

Joan was born in Madrid. Her father was King of Aragon and King of Castile, the first to rule the united Spain, as well as Holy Roman Emperor. Joan was therefore also an Infanta of Spain as well as an Archduchess of Austria, part of the powerful Habsburg family.

Joan was married in 1552 to John Manuel, Infante of Portugal and expected heir to that throne. He was her double first cousin. The Habsburg family tended to marry cousins; both their parents were also first cousins of each other. Joan and John Manuel shared the same grandmothers, who were sisters: Joanna I and Maria, daughters of Queen Isabella of Castile and King Ferdinand of Aragon. They also shared the same two grandfathers: Philip I of Castile and Manuel I of Portugal.


1554 was a momentous year. John Manuel had always been sickly, surviving four brothers who died before him. On January 2, when Joan was pregnant with her first child, John Manuel died, of consumption or diabetes. He was only 16 years old.

On the 20th of that month, Joan gave birth to their son Sebastian. When his paternal grandfather John III died three years later, Sebastian became king. His paternal grandmother, Catherine of Austria, was regent for Sebastian from 1557 to 1562.

But Joan left later in 1554 for Spain, without her son. Her brother, Philip II, had married the English Queen Mary I, and Philip joined Mary in England. Joan never saw her son again, though they corresponded.

Convent of the Poor Clares

In 1557, Joan founded a convent for the Poor Clares, Our Lady of Consolation. She also supported the Jesuits. Joan died in 1578, only 38 years old, and was buried at the convent she had founded, which became known as the Convent of Las Descalzas Reales.

Sebastian's Fate

Sebastian never married, and died on August 4, 1578, in battle when attempting a crusade against Morocco. He was only 22 years old. Myths of his survival of the battle and imminent return led to him being called The Desired (o Desejado).

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Lewis, Jone Johnson. "Isabella of Portugal (1503 - 1539)." ThoughtCo, Apr. 5, 2023, Lewis, Jone Johnson. (2023, April 5). Isabella of Portugal (1503 - 1539). Retrieved from Lewis, Jone Johnson. "Isabella of Portugal (1503 - 1539)." ThoughtCo. (accessed June 4, 2023).