The Medieval Inquisition was a series of Inquisitions (Catholic Church bodies charged with suppressing heresy) from around 1184, including the Episcopal Inquisition (1184–1230s) and later the Papal Inquisition (1230s). The Medieval Inquisition was established in response to movements considered apostate or heretical to Roman Catholicism, in particular Catharism and Waldensians in Southern France and Northern Italy. These were the first movements of many inquisitions that would follow.

The Cathars were first noted in the 1140s in Southern France, and the Waldensians around 1170 in Northern Italy. Before this point, individual heretics such as Peter of Bruis had often challenged the Church. However, the Cathars were the first mass organization in the second millennium that posed a serious threat to the authority of the Church. This article covers only these early inquisitions, not the Roman Inquisition of the 16th century onwards, or the somewhat different phenomenon of the Spanish Inquisition of the late 15th century, which was under the control of the Spanish monarchy using local clergy. The Portuguese Inquisition of the 16th century and various colonial branches followed the same pattern.