Catherine Eliza Somerville Stow, who wrote as K. Langloh Parker, was a South Australian born writer who lived in northern New South Wales in the late nineteenth century. She is best known for recording the stories of the Ualarai around her. Her testimony is one of the best accounts of the beliefs and stories of an Aboriginal people in north-west New South Wales at that time. However, her accounts reflect European attitudes of the time.

Gibran Khalil Gibran, usually referred to in English as Kahlil Gibran, was a Lebanese-American writer, poet and visual artist; he was also considered a philosopher, although he himself rejected the title. He is best known as the author of The Prophet, which was first published in the United States in 1923 and has since become one of the best-selling books of all time, having been translated into more than 100 languages.

Kālidāsa was a Classical Sanskrit author who is often considered ancient India's greatest poet and playwright. His plays and poetry are primarily based on Hindu Puranas and philosophy. His surviving works consist of three plays, two epic poems and two shorter poems.

Kálmán Mikszáth de Kiscsoltó was a widely reputed Hungarian novelist, journalist, and politician. His work remains in print in Hungarian and still appears from time to time in other languages.

Karel Čapek was a Czech writer, playwright, critic and journalist. He has become best known for his science fiction, including his novel War with the Newts (1936) and play R.U.R., which introduced the word robot. He also wrote many politically charged works dealing with the social turmoil of his time. Influenced by American pragmatic liberalism, he campaigned in favor of free expression and strongly opposed the rise of both fascism and communism in Europe.

Karl Emil Franzos was a popular Austrian novelist of the late 19th century. His works, both reportage and fiction, concentrate on the multi-ethnic corner of Galicia, Podolia and Bukovina, now largely in western Ukraine, where the Habsburg and Russian empires met. This area became so closely associated with his name that one critic called it "Franzos country". A number of his books were translated into English, and Gladstone is said to have been among his admirers.

Karl Friedrich Becker was a German educator and historian. His most noted work was World History for Children and Teachers of Children which was widely used and much edited and revised by other noted historians after Becker's death.

Karl Groos was a German philosopher and psychologist who proposed an evolutionary instrumentalist theory of play. His 1898 book on The Play of Animals suggested that play is a preparation for later life.

Karl Heinrich Marx was a German-born philosopher, economist, historian, sociologist, political theorist, journalist, critic of political economy, and revolutionary socialist. His best-known works are the 1848 pamphlet The Communist Manifesto and the three-volume Das Kapital (1867–1894); the latter employs his theory of historical materialism in an analysis of capitalism, representing his greatest intellectual achievement. His theories and ideas, and their subsequent development, are collectively known as Marxism, and have exerted enormous influence on intellectual, economic, and political history.

Karl Friedrich May was a German author. He is best known for his 19th century novels of fictitious travels and adventures, set in the American Old West with Winnetou and Old Shatterhand as main protagonists and in the Orient and Middle East with fictional characters Kara Ben Nemsi and Hadschi Halef Omar.