The name is found in United States records from the 19th century; the name Wendy appeared over twenty times in the U.S. Census of 1880. In Britain, Wendy appeared as a boy’s name in the 1881 census of England, and was occasionally used as a diminutive for the Welsh Gwendolyn. It was also used as a surname in Britain from at least the 17th century.
Various Chinese rulers have held the name and title Emperor Wen, which in Chinese is read Wen(-)di (文帝). Chinese women with the same or similar-sounding characters as their given names often anglicise their names as Wendi or Wendy (e.g. Wendi Deng,Wendy Kweh).
In Germany, the name Wendy became popular because of a children’s magazine series about horses.