The Fatal Vespers was a 1623 structural collapse at Hunsdon House in Blackfriars, London, England, the official residence of the French ambassador.

On the afternoon of Sunday, 26 October (Old Style) 1623 about three hundred persons assembled in an upper room at Hunsdon House for the purpose of participating in a religious service led by Robert Drury and William Whittingham, two Jesuits.

[1] A circumstantial account of the incident was provided in The Doleful Even-Song (1623), by Thomas Goad,[3] and another contemporary description is given in The Fatall Vesper (1623), bearing the initials "W. C." and erroneously ascribed to William Crashaw, father of the poet.

[4] The disaster was the subject of a broadside ballad, The dismall day at the Black-Fryers, or, A deplorable elegie on the death of almost an hundred persons, who were lamentably slaine by the fall of a house in the Blacke-Fryers: being all assembled there (after the manner of their devotions) to heare a sermon on Sunday night, the 26 of October last past, An.

[1][5] In response Father John Floyd wrote A Word of Comfort to the English Catholics, published as a quarto volume in Saint-Omer in 1623.