Karl Kraus was an Austrian writer and journalist, known as a satirist, essayist, aphorist, playwright and poet. He directed his satire at the press, German culture, and German and Austrian politics. He was nominated for the Nobel Prize in Literature three times.

Karl Kroeber was an American literary scholar, known for his writing on the English Romantics and American Indian literature. He was the son of Theodora and Alfred L. Kroeber, both anthropologists. He wrote an account of his father's work with Ishi called Ishi in Three Centuries.

Karl Krolow was a German poet and translator. In 1956 he was awarded the Georg Büchner Prize. He was born in Hanover, Germany, and died in Darmstadt, Germany.

Karl Krumbacher was a German scholar who was an expert on Byzantine Greek language, literature, history and culture. He was one of the principal founders of Byzantine Studies as an independent academic discipline in modern universities.

Karl Sven Woytek Sas Konkovitch Matthew Kruszelnicki, often referred to as "Dr Karl", is an Australian science communicator and populariser, who is known as an author and a science commentator on Australian radio and television.

Karl Konrad Friedrich Wilhelm Lachmann was a German philologist and critic. He is particularly noted for his foundational contributions to the field of textual criticism.

Karl Gotthard Lamprecht was a German historian who specialized in German art and economic history.

Karl Leonhard Reinhold was an Austrian philosopher who helped to popularise the work of Immanuel Kant in the late 18th century. His "elementary philosophy" (Elementarphilosophie) also influenced German idealism, notably Johann Gottlieb Fichte, as a critical system grounded in a fundamental first principle.

Karl Ludwig Costenoble, also Carl Ludwig Costenoble, was a German stage actor, theatre director and writer.

Karl Friedrich Ludwig Kannegiesser (1781-1861) was a German author, translator, and critic.