The 𝐒𝐭. 𝐁𝐚𝐫𝐭𝐡𝐨𝐥𝐨𝐦𝐞𝐰'𝐬 𝐃𝐚𝐲 𝐌𝐚𝐬𝐬𝐚𝐜𝐫𝐞 took place beginning on 𝐀𝐮𝐠𝐮𝐬𝐭 𝟐𝟒, 𝟏𝟓𝟕𝟐, in Paris and spreading across France, resulting in the deaths of an estimated 30,000 French Huguenots.

The Third War of Religion in France between Roman Catholics and Protestant Huguenots had come to a negotiated end in 1570. Henry III of Navarre and Margaret of Valois were married in Paris on August 18, 1572, and consequently, a large number of leading French Huguenots were in the city for the event.

On August 22, while walking home, French Huguenot Admiral Gaspard de Coligny was shot in the street by an unknown assailant who escaped. He was severely injured, but recuperating at home when, at the instigation of Margaret's mother, Queen Catherine de' Medici (mother of King Charles IX), Henry, Duke of Guise and his men finished the job by stabbing Coligny and throwing him out of his window.

This led to a widespread, semi-organized wave of violence against French Huguenot leaders and citizens. Bodies were thrown into the River Seine (over 1000 washed ashore in the coming days). Petrus Ramus, the philosopher, was killed in Paris, and Claude Goudimel, the composer who played a major role in the production of the Genevan Psalter, was killed in Lyon. The severed head of Coligny was sent to the Pope (but apparently not delivered), and the Pope rejoiced in the slaughter of the Hugenots, celebrating with a gold medal created for the occasion, and ordering a Te Deum to be sung to God in thanksgiving for the event. When Philip I of Spain heard the news, he "laughed, for almost the only time on record."

English playwright Christopher Marlowe wrote a play to tell the story called 𝑇ℎ𝑒 𝑀𝑎𝑠𝑠𝑎𝑐𝑟𝑒 𝑎𝑡 𝑃𝑎𝑟𝑖𝑠 (1593), and the massacre has been retold in many other works of literature since. It was one of the most infamous atrocities ever perpetrated against Christians since the time of the Reformation.