How many female monarchs have reigned between Elizabeth I and Elizabeth II?

There have been three female monarchs that have reigned between Elizabeth I (September 9, 1533 - March 24, 1603) and Elizabeth II (April 21, 1926 -).

The first to reign was Mary II (April 30, 1662 - December 28, 1694). Mary assumed the throne as co-ruler with her husband when it was feared that her father would restore Roman Catholicism. Mary II died childless in 1694 of smallpox, only 32 years old.

The second to reign was Queen Anne (February 6, 1665 - August 1, 1714). Sister of Mary II, Anne succeeded to the throne when her brother-in-law William III died in 1702. She was married to Prince George of Denmark, and though she was pregnant 18 times, she had only one child who survived infancy.

The third to reign was Queen Victoria (May 24, 1819 - January 22, 1901). Queen Victoria of the United Kingdom was the longest-ruling monarch of Great Britain until Queen Elizabeth II. She ruled during a time of economic and imperial expansion, and gave her name to the Victorian Era. She married a cousin, Prince Albert of Saxe-Coburg and Gotha, when they were both seventeen years old, and had seven children before his death in 1861 sent her into a long mourning period.