In Arthurian legend, the Siege Perilous (also known as The Perilous Seat) is a vacant seat at the Round Table reserved by Merlin for the knight who would one day be successful in the quest for the Holy Grail. This knight is either Percival or Sir Galahad, depending on the version of the story. The Siege Perilous is so strictly reserved that it is fatal to anyone else who sits in it.
- Malory T., Morte Darthur, The Globe Edition, Macmillan and Co., London 1868, Book XI, p.326: "he shall be born that shall sit there in that siege perilous, and he shall win the Sangreal." Facsimile by Google Books
- Tennyson, A., Idylls of the King, 1856: "And Merlin called it 'The Siege perilous'"(forgottenbooks.org 2007 edition at Google Books)