Pope Joan was a legendary woman said to have reigned as head of the Catholic Church from 855 to 857, while keeping her gender secret. Her story first appeared in the 13th century and came to be accepted as true in most of Europe before being disproven during the Reformation.
Most versions of the tale wax about a talented, erudite woman who disguised herself as a man and who rose through the church hierarchy and was eventually elected to lead the world’s Catholics. Her sex was revealed when she gave birth during a procession, after which was either murdered or whisked away. Of course, if she had been a quick enough thinker, she would have claimed that her miraculous ability to give birth as a man was a sign she was chosen by God.
The first known reference to a female pope came around 1250 in a chronicle penned by Jean de Mailly. This account inspired several more versions, embellishments, and reworkings over the next few centuries. The most popular and influential version was written by Martin of Opava. Historians credit him with giving her a name, specifying when she ruled, and adding a steamy tidbit that Joan concocted the elaborate schemed to aid her lover.
The legend was generally accepted as true until the 16th century, when a widespread debate among Catholic and Protestant writers called the story into question. They noted the multi-century gap between her supposed reign and the first accounting of it. As much as is written about and by the Catholic Church, the idea that not even one scrap of evidence of Pope Joan would exist until three centuries after her lifetime seems untenable.
Proponents of a Pope Joan point to a reference in a chronicle written by Anastasius Bibliothecarius, a contemporary of de Mailly. However, this fleeting reference is inserted as a footnote, is out of sequence, and is written in a different hand.
The legend began to unravel when parliamentary magistrate Florimond de Raemond looked into Joanian texts with the goal of giving historical context to the story. Rather than finding the clues he was hoping to, de Raemond found a loosely-assembled, contradictory, meandering fairy tale entirely lacking in authenticated documentation. Neither de Raemond nor any other investigator ever found any reference or evidence of a Pope Joan during the years of her supposed reign.
This includes church enemies who would have been only too happy to highlight it and embarrassment to the Vatican. Imagine, an institution with immense power, wealth, and privilege, and which denies leadership positions to females, being bamboozled by a woman and spending two years unable to figure it out. Besides, the pontiffs Leo IV and Benedict III were known to have been reigning during the time in question.