Notable bearers of this name include the Greek philosopher and mathematician Theon of Smyrna (2nd century AD) and the Greek scholar and mathematician Theon of Alexandria (4th century AD).
In modern literature, this name is best known for being the name of Theon Greyjoy, a character from the A Song of Ice and Fire series of fantasy novels written by the American author George R. R. Martin (b. 1948). He also appears in Game of Thrones (2011-2019), a television series based upon the novels.