Valdemar Langlet [lan’lé] (December 17, 1872 in Lerbo, Sweden – October 16, 1960 in ) was a Swedish publisher, and an early Esperantist. With his wife Nina Borovko-Langlet in Budapest, he is credited with saving many Jews from the Holocaust, by providing Swedish documents saying that people were waiting for Swedish nationality. Raoul Wallenberg was inspired by Langlet and used the same method to save Jewish people when he came to Budapest. In 1965, Valdemar and Nina Langlet were recognized as Righteous Among the Nations by Yad Vashem.
After his student years (in Germany, Austria and Switzerland) he worked as an engineer, and later journalist and editor of many Swedish newspapers (among others, Svensk Handelstidning and Svenska Dagbladet. He wrote books about current affairs and about voyages to Russia and Hungary. In 1890, he learned Esperanto, and was a founding member of the Esperanto club of Uppsala in 1891, the second Esperanto club in the world, and for many years he served as president of the club. When the Swedish Esperanto Federation was founded in 1906, he became its president, until the great Ido-schism during Easter of 1909.
In 1899, he married a Finnish esperantist Signe Blomberg from Turku. After her death in 1921, he met Nina Borovko, the daughter of Nikolai Afrikanovich Borovko, a friend and a pioneering Esperantist in Russia. In 1925, Valdemar and Nina married.
In 1932, Langlet was hired by the University of Budapest, where he served as lecturer on the Swedish language. At the same time, he worked as an officer in the Swedish Embassy in Budapest.