Pornocracy is a term that has been used to mean government or domination of government by prostitutes.
In history, it refers specifically to a period of papacy in the early tenth century, beginning with Pope Sergius III from 904 and ending with the death of John XII in 963. During this period, the popes were under the influence of corrupt women (though not necessarily prostitutes), especially Theodora and her daughter, Marozia. This period is also called the Rule of the Harlots.
It is popularly believed that Marozia was the concubine of Sergius III and the mother of Pope John XI. She was also accused of having had John X murdered (who had originally been nominated for office by Theodora) in order to secure the election of her current favourite, Leo VI.
Theodora and Marozia undoubtedly held great sway over the popes during this time. In particular, as political rulers of Rome they had effective control over the election of new popes. However, it is debatable whether all of the allegations that have been made against them can be substantiated. Much of the evidence for the time comes from the histories of Liutprand, bishop of Cremona. Liutprand took part in the Assembly of Bishops which deposed John XII and was a political enemy of Rome; he is described by the Catholic Encyclopedia as ever a strong partisan and frequently unfair towards his adversaries. The worst excesses of the time might be considered no more than ecclesiastical gossip.