The Letterist International (LI) (L'Internationale lettriste (I.L.)) was a Paris-based collective of radical artists and cultural theorists between 1952 and 1957. It was created by Guy Debord and Gil J. Wolman rejoined by Jean-Louis Brau and Serge Berna as a schism from Isidore Isou's Lettrist group. The group went on to join others in forming the Situationist International, taking some key techniques and ideas with it.
'Letterist' (lettriste) was the form the group themselves used, as in their 1955 sticker: 'If you believe you have genius, or if you think you have only a brilliant intelligence, write the letterist internationale.' Though the spelling 'Lettrist' is also common in English, authors and translators such as Donald Nicholson-Smith, Simon Ford, Sadie Plant and Andrew Hussey use the 'Letterist International' spelling.