Cleidemus was a Greek author, perhaps of the fifth or fourth century BCE but definitely later than the battle of Plataea in 479 BCE, who produced a lost Atthis (Ἀτθίς), a local history of Athens dealing with the traditional origins of the city's law and institutions. Johannes Meursius suggested that "Cleidemus" is actually identical with the "Cleitodemus" stated by Pausanias to be the most ancient writer on Athenian history. Athenaeus and Plutarch make references to his works, all of which are lost.
Cleinias of Tarentum was a Pythagorean philosopher, and a contemporary and friend of Plato, as appears from the story which Diogenes Laërtius gives on the authority of Aristoxenus, to the effect that Plato wished to burn all the writings of Democritus which he could collect, but was prevented by Cleinias and Amyclus of Heraclea. In his practice, Cleinias was a true Pythagorean. Thus, we hear that he used to assuage his anger by playing on his harp; and, when Prorus of Cyrene had lost all his fortune through a political revolution, Cleinias, who knew nothing of him except that he was a Pythagorean, took on himself the risk of a voyage to Cyrene, and supplied him with money to the full extent of his loss.
Cleitarchus or Clitarchus was one of the historians of Alexander the Great. Son of the historian Dinon of Colophon, he spent a considerable time at the court of Ptolemy Lagus. He was active in the mid to late 4th century BCE.
Clem Schouwenaars was a Belgian writer. He grew up in a Roman Catholic family. Two of his brothers and one of his sisters died young, and his only remaining sister was killed during a bombardment in 1943. His mother died in 1960, and some time later his father committed suicide.
Clement Allan Tisdell was an Australian economist and Emeritus Professor at the University of Queensland. He was best known for his work in environmental and ecological economics.
Clemence Annie Housman was an author, illustrator and activist in the women's suffrage movement. She was the sister of A. E. Housman and Laurence Housman. Her novels included The Were-Wolf, Unknown Sea and The Life of Sir Aglovale De Galis. She was also a leading figure in the suffragette movement.
Clémence Royer was a self-taught French scholar who lectured and wrote on economics, philosophy, science and feminism. She is best known for her controversial 1862 French translation of Charles Darwin's On the Origin of Species.
Clemens Georg Arvay was an Austrian author of nonfiction books with an emphasis on health ecology. In particular, his controversial conclusions about the relationship between the benefit and risk of the corona vaccines attracted media attention.
