Mary I, also known as Mary Tudor, and as "Bloody Mary" by her Protestant opponents, was Queen of England and Ireland from July 1553 and Queen of Spain and the Habsburg dominions as the wife of King Philip II from January 1556 until her death in 1558. She is best known for her vigorous attempt to reverse the English Reformation, which had begun during the reign of her father, King Henry VIII. Her attempt to restore to the Church the property confiscated in the previous two reigns was largely thwarted by Parliament, but during her five-year reign, Mary had over 280 religious dissenters burned at the stake in the Marian persecutions.

Philip II, also known as Philip the Prudent, was King of Spain from 1556, King of Portugal from 1580, and King of Naples and Sicily from 1554 until his death in 1598. He was also jure uxoris King of England and Ireland from his marriage to Queen Mary I in 1554 until her death in 1558. He was also Duke of Milan from 1540. From 1555, he was Lord of the Seventeen Provinces of the Netherlands.