Catherine of Aragon (Spanish: Catalina de Aragón; Catalina de Trastámara y Trastámara) (16 December 1485 – 7 January 1536), also known as Katherine or Katharine, is Queen of England as the first wife of King Henry VIII of England and Princess of Wales as the wife to Arthur, Prince of Wales.

In 1507, she also holds the position of Ambassador for the Spanish Court in England when her father finds himself without one, becoming the first female ambassador in European history.

For six months, she serves as Queen Regent of England while Henry VIII is in France.

During that time the English win the Battle of Flodden, an event in which Catherine plays an important part.

The controversial book "The Education of Christian Women" by Juan Luis Vives, which claims women have the right to an education, is dedicated to and commissioned by her.

Such is Catherine's impression on people, that even her enemy, Thomas Cromwell, says of her "If not for her sex, she could have defied all the heroes of History."

William Shakespeare described her as "The Queen of Earthly Queens", and during her early years as queen consort she is described as "The most beautiful creature in the world."

She successfully appeals for the lives of the rebels involved in the Evil May Day for the sake of their families.

Furthermore, Catherine wins widespread admiration by starting an extensive program for the relief of the poor.

She is also a patron of Renaissance humanism, and a friend of the great scholars Erasmus of Rotterdam and Saint Thomas More.

Henry VIII's move to have their 24-year marriage annulled sets in motion a chain of events that lead to England's break with the Roman Catholic Church.

Henry is dissatisfied because their sons had died in infancy and others were stillborn, leaving their daughter, the future Mary I of England, as heiress presumptive, at a time when there is no established precedent for a woman on the throne, although there is no Salic law in England.

When Pope Clement VII refuses to annul the marriage, Henry defies him by assuming supremacy over religious matters.

This allows him to marry Anne Boleyn on the judgment of clergy in England, without reference to the Pope.

He is motivated by the hope of fathering a male heir to the Tudor dynasty.

Catherine refuses to accept Henry as Supreme Head of the Church of England and considers herself, as do most of England and Europe, the King's rightful wife and Queen until her death.