Gaius m. Latin Gaius or Caius, one of the most common Roman praenomina. The origin is uncertain, but it may be related to Latin gaudere 'to rejoice'.
The name of a number of minor New Testament characters, a 3rd C saint, a 3rd C pope, as well as the praenomen of Julius Caesar, Pliny the Elder, and Tacitus. Wycliffite Bible (1395): Gayus.