Spurius Carvilius Ruga

Spurius Carvilius Rūga (, ) was the freedman of Spurius Carvilius Maximus Ruga. He is often credited with inventing the Latin letter G. His invention would have been quickly adopted in the Roman Republic, because the letter C was used for both the and sounds. For example, Ruga's own name contained this ambiguity. In the latter half of the 3rd century BC, Ruga is the first man recorded to have been attested as opening a private elementary school, although other such schools may have existed in Rome prior to his.

Plutarch is the main source for these inventions, and Quintus Terentius Scaurus confirms the former in . The letter G was already in use before 230 BC; Wilhelm Paul Corssen theorized in that Plutarch intended to communicate that Ruga's school was the first to assign C and G to the phonemes of and .