Nicolas Camille Flammarion FRAS was a French astronomer and author. He was a prolific author of more than fifty titles, including popular science works about astronomy, several notable early science fiction novels, and works on psychical research and related topics. He also published the magazine L'Astronomie, starting in 1882. He maintained a private observatory at Juvisy-sur-Orge, France.

Antoine Louis Camille Lemonnier was a Belgian writer, poet and journalist. He was a member of the Symbolist La Jeune Belgique group, but his best known works are realist. His first work was Salon de Bruxelles (1863), a collection of art criticism. His best known novel is Un Mâle (1881).

Séverin Faust, better known by his pseudonym Camille Mauclair, was a French poet, novelist, biographer, travel writer, and art critic.

David Caradoc Evans, was a Welsh story writer, novelist and playwright.

Carl Ewald was a Danish novelist and satirist known for his fairy tales.

Carl Gustav Jung was a Swiss psychiatrist and psychoanalyst who founded analytical psychology. Jung's work has been influential in the fields of psychiatry, anthropology, archaeology, literature, philosophy, psychology, and religious studies. He worked as a research scientist at the Burghölzli psychiatric hospital, in Zurich, under Eugen Bleuler. Jung established himself as an influential mind of his time, developing a friendship with Sigmund Freud, founder of psychoanalysis, conducting a lengthy correspondence, paramount to their joint vision of human psychology. He is regarded as one of the most influential psychologists in history.

Carl Kelsey was an American sociologist and professor of sociology at the University of Pennsylvania.

Carl Lotus Becker was an American historian who studied the American Revolution and the Age of Enlightenment in America and Europe.

Carl Linnaeus, also known after his ennoblement in 1761 as Carl von Linné, was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the modern system of naming organisms. He is known as the "father of modern taxonomy". Many of his writings were in Latin; his name is rendered in Latin as Carolus Linnæus and, after his 1761 ennoblement, as Carolus a Linné.

Carl Richard Jacobi was an American journalist and writer. He wrote short stories in the horror and fantasy genres for the pulp magazine market, appearing in such pulps of the bizarre and uncanny as Thrilling, Ghost Stories, Startling Stories, Thrilling Wonder Stories and Strange Stories. He also wrote stories crime and adventure which appeared in such pulps as Thrilling Adventures, Complete Stories, Top-Notch, Short Stories, The Skipper, Doc Savage and Dime Adventures Magazine. Jacobi also produced some science fiction, mainly space opera, published in such magazines as Planet Stories. He was one of the last surviving pulp-fictioneers to have contributed to the legendary American horror magazine Weird Tales during its "glory days". His stories have been translated into French, Swedish, Danish and Dutch.