Robert Charroux was the best-known pen-name of Robert Joseph Grugeau. He was a French author known for his writings on the ancient astronaut theme.

Robert Chartham was the pseudonym of Ronald Sydney Seth, an English writer who used the surname Chartham for his activity as a sexologist and the surname Seth for books about travel and espionage.

Robert Christian Barthold Avé-Lallemant was a German physician and explorer who was a native of Lübeck. He was a brother to criminologist Friedrich Christian Benedict Avé-Lallemant (1809–1892) and music critic Theodor Avé-Lallemant (1806–1890).

Robert Beno Cialdini is an American psychologist. He is the Regents' Professor Emeritus of Psychology and Marketing at Arizona State University and was a visiting professor of marketing, business and psychology at Stanford University.

Robert Beno Cialdini is an American psychologist and author. He is the Regents' Professor Emeritus of Psychology and Marketing at Arizona State University and was a visiting professor of marketing, business and psychology at Stanford University.

Robert Colby was an American songwriter, music publisher and theatrical producer. Among his songs were "Jilted" and "Free Again". He composed the music and lyrics for the 1962 Off-Broadway musical Half-past Wednesday, based on the fairy tale Rumpelstiltskin. He produced the 1968 Paul Mauriat hit recording of Love is Blue.

George Robert Acworth Conquest was a British-American historian and poet.

Robert Constantin was a 16th-century French physician, hellenist, bibliographer, lexicographer and humanist.

Robert Lowell Coover is an American novelist, short story writer, and T.B. Stowell Professor Emeritus in Literary Arts at Brown University. He is generally considered a writer of fabulation and metafiction.

Robert Edmund Cormier was an American author and journalist, known for his deeply pessimistic novels, many of which were written for young adults. Recurring themes include abuse, mental illness, violence, revenge, betrayal, and conspiracy. In most of his novels, the protagonists do not win.