Karl Robert Langewiesche (18 December 1874 in Rheydt – 12 September 1931 in Königstein im Taunus) was a German publisher.
In 1902 he founded the Verlag Langewiesche in Düsseldorf, one of the oldest book publishers in Germany still operating.
Son of a bookseller, Langewiesche founded his publishing company on 5 May 1902 with the goal to produce "distinguished mass-produced articles at the lowest prices" in order to make them available, "especially to the broad masses: those who are called uneducated, who may become so through my work."
He is regarded as the inventor of the publisher-issued shop window poster and for the blurb (German: Klappentext).
For the firm's 25th anniversary, he founded, under the motto "Good for All" an even cheaper label, "The Iron Hammer" (renamed in 1949 as the Langewiesche Library) with red covers.