The Black Book of Chirk (Welsh: Llyfr Du o'r Waun) is a 13th-century Welsh language manuscript, known also as the Chirk Codex. It is Peniarth 29 of the National Library of Wales, and deals with legal and historical matters. This was one of the collection of manuscripts amassed at the mansion of Hengwrt, near Dolgellau, Gwynedd, by Welsh antiquary Robert Vaughan (c. 1592 – 1667); the collection later passed to the newly established National Library of Wales as the Peniarth or Hengwrt-Peniarth Manuscripts.