Final answer:
The term "Bloody Mary" refers to Mary I of England, known for her persecution and execution of Protestants in an attempt to restore Catholicism in England during her reign from 1553 to 1558.
Step-by-step explanation:
The term for the monarch called "Bloody" because of her many executions of Protestants is Bloody Mary. This nickname was given to Mary I of England, the daughter of Henry VIII and his first wife Catherine of Aragon. Mary I was a staunch Catholic and during her reign from 1553 to 1558, she attempted to restore England to Catholicism, which resulted in the persecution and execution of several hundred Protestants. Her attempts to enforce Catholicism and the subsequent violence against Protestants earned her the infamous nickname Bloody Mary.
Mary I's religious policies stood in stark contrast to the Protestant reforms initiated by her half-brother Edward VI and the later moderate approaches of her half-sister Elizabeth I. Her reign is particularly noted for the intensity of religious violence, which was common during the age characterized by religious intolerance.