Lettow meant "Lithuania" in the Saxon language, and it appears in the General Prologue to The Canterbury Tales, wherein it is said of the Knight, a veteran of the Baltic Crusades: "Ful ofte tyme he hadde the bord bigonne / Aboven alle nacions in Pruce; / In Lettow hadde he reysed, and in Ruce, / No Cristen man so ofte of his degree.
"[1] With a few variants like Lettau, Lettaw, Litav, Littauer or Littawer, it was also adopted by some other Vorbe(c)ks in Pomerania as a surname.
In Lithuania, later on, it was spelled Lettowt or Letowt, before the 20th century Lithuanian surname policy changed it to Letautas.
John Lettou was a 15th century bookbinder and printer in England, presumably a German from the Grand Duchy of Lithuania.
Today, most people with the surname Lettow live in Germany and the United States, some in Holland as van Lettow, and a few in Austria, Latvia, the United Kingdom, South Africa, Canada, South America, and even in China (in the 20th century several Letowts lived and worked in Harbin and Shanghai).