This is an alphabetical list of any individuals, legendary or real, who are purported by traditions to have invented alphabets or other writing systems, whether this is proven or not.
Cadmus - legendary Phoenician prince, ascribed invention of Greek alphabet c. 1350 BC (?) according to tradition.
Cangjie - legendary Chinese scribe, also ascribed invention of Chinese characters c. 2650 BC (?) according to tradition.
Carmenta - legendary Roman prophetess and mother of Evander, ascribed adoption of Greek alphabet to Latin alphabet c. 1250 BC (?) according to tradition.
C.C. Elian (artist) - invented Elian script, c. 1980s, a transformation of the Latin alphabet into lines and dashes, allowing for multiple variations of the same word.
Frumentius - Syrian saint who converted the African kingdom of Aksum to Christianity, traditionally credited with development of consonantal Ge'ez script into vocalic Ge'ez script in the mid 4th-century.
Fu Hsi - legendary Chinese king, ascribed invention of Chinese characters c. 2850 BC (?) according to tradition.
W. John (or John W.) Weilgart - Austrian-born American psychoanalyst and philosopher; creator of the philosophical language aUI and its writing system.