You might, perhaps, have heard that there was once a female pope. Those people were talking about Pope Joan, who was supposedly in charge some time around 850 or 1000.
What's the story?
As you might expect, there are several different versions of her story. This is an amalgamation of the most common.
Joan was very intelligent and she wanted to be a scholar, so, she did the only logical thing in a world that refused learning to women: pretended to be a man. Some versions make this her own decision, and others make it the request of a lover.
She was greatly successful in Athens, and eventually moved to Rome where she was became an expert in a diverse range of subjects. Somewhere along the line she became a priest, and rose quickly through the church ranks. When the old pope died, she was chosen to succeed him.
The length of her reign is unclear: some accounts say it was only a few months, but others give it as several years. At some point, she became pregnant, presumably by one of the priests who attended her, and while riding a horse in a papal procession, she gave birth.
Which was a bit of a shock for most of the followers, given that the pope had just given birth. Here's a pretty epic illustration of that event. It dates from 1539.
Most accounts say she was stoned to death outside the city, but one suggests she retired and did many years of penance.
What's the evidence?
Unfortunately, there are a few real historical problems:
As mentioned above, she's supposed to have been pope around 850 or 1000. However, she first appears in the historical record in the mid- 13th century, in a chronicle by Jean de Mailly, who places her around 1000. It is likely the story is older, but we cannot know how much older, or how accurate it is. He does not give her a name, and only writes: 'Concerning a certain Pope or rather female Pope, who ...was a woman who disguised herself as a man and became, by her character and talents, a curial secretary, then a Cardinal
and finally Pope. One day, while mounting a horse, she gave birth to a
child. Immediately, ... she was bound by the feet to a
horse's tail and dragged and stoned by the people for half a league,
and, where she died.'- Jean de Mailly, Chronica Universalis Mettensis
She was later named by Martin of Opava in the third iteration of her tale, who calls her 'John Angelicus'. This later evolved to 'Joan'. Martin's version is from later in the 13th century, and moves the date of her reign back to the 9th century.
After the 13th century, the fable was widely believed, and there were several more works that mention her from the Middle Ages and Renaissance periods. However, it is unlikely that any of them have sources other than those listed above, and their imaginations.
She has now been widely discredited.
So why is she so popular?
I think this question sort of answers itself. Joan was awesome. She was clever and cunning, and she outwitted those stuffy priests and made herself Queen of the World. Practically. She makes for a great story, and who doesn't love a good story?