Klaus Hildebrand is a German liberal-conservative historian whose area of expertise is 19th–20th-century German political and military history.

Klaus Mainzer is a German philosopher and scientist. Mainzer is the president of the European Academy of Sciences and Arts. He is the author of the widely translated, cited, and reviewed book Thinking in Complexity.

Klaus Heinrich Thomas Mann was a German writer and dissident. He was the son of Thomas Mann, a nephew of Heinrich Mann and brother of Erika Mann and Golo Mann. He is well known for his 1936 novel, Mephisto.

Klaus Merz, is a Swiss writer.

Klaus Modick is a German author and literary translator.

Klaus Ottmann is a writer, art curator and publisher. He is currently deputy director for Academic Affairs and Special Projects at The Phillips Collection in Washington, D.C.

Klaus Rifbjerg was a Danish writer. He authored more than 170 novels, books and essays. In 1965 he co-produced the film 4x4 which was entered into the 4th Moscow International Film Festival.

Klaus D. Schmidt is an Austrian mathematician and retired professor at the Faculty of Mathematics, University of Vienna.

Klaus Theweleit is a German sociologist and writer.

Klaus Vogel (1930–2007), born in Hamburg, Germany, was widely recognized as an academic expert on the aspects of international taxation, particularly on tax treaties. He is regarded as having been an authority on the interpretation of double tax treaties.