A Macedonian, Paul’s fellow-traveller, and his host at Corinth when he wrote his Epistle to the Romans (16:23). He with his household were baptized by Paul (1 Cor. 1:14). During a heathen outbreak against Paul at Ephesus the mob seized Gaius and Aristarchus because they could not find Paul, and rushed with them into the theatre. Some have identified this Gaius with No. (2).