Gaius Terentius Tullius Geminus was a Roman senator of the early Roman Empire, who flourished under the reign of Claudius. He was suffect consul in the nundinium of September-December 46 as the colleague of Marcus Junius Silanus.^[1] It is inconclusive if a poet named Tullius Geminus, whose poems are included in the Palatine Anthology is the same man.^[2]

Although Steven Rutledge dates the start of his senatorial career to the reign of Tiberius,^[2] the earliest attested event in Geminus' life is his suffect consulship. He is attested as governor of Moesia in the 50s; a copy of a letter he wrote to the inhabitants of Histria upholding their rights to the mouth of the Danube was preserved in a set of inscriptions known as the Horothesia Laberiou Maximou.^[3] Geminus appears in the Annales of Tacitus, as prosecuting Aulus Didius Gallus Fabricius Veiento at the direction of the emperor Nero for allegedly writing a collection of lampoons on senators and pontiffs called "Codicils"; Veiento was found guilty, banished from Italy, and copies of the pamphlets burned.^[4]