John Lettou or John of Lithuania (Belarusian: Ян Літвін, Lithuanian: Jonas Lietuvis, fl. 1475–1483) was an English bookbinder and printer. He was probably of Baltic origin, since his last name was the Middle English form for Lithuania, at that time the state Great Duchy of Lithuania covering the territory of modern Belarus, Ukraine and Lithuania.
Seventeen books printed between 1475 and 1480 are attributed to the workshop of the ‘Indulgence Binder’ now identified as Lettou. The identification depends upon the use of waste strips cut from an indulgence of 1480 used in the binding of a Bible, printed by Gotz in 1480, which now belongs to Jesus College, Cambridge. Since this waste would have been found only in the workshop of the printer, and the indulgence was printed by Lettou, he must have been both the printer and the binder. John Lettou also published in partnership with William de Machlinia and they published mostly law books.