Gaius Memmius (died circa 49 BC, incorrectly called Gemellus, "The Twin") was a Roman orator and poet. He was Tribune of the Plebs (66 BC), possibly a patron of Lucretius, and an acquaintance of Catullus and Helvius Cinna. His sister Memmia was married to Gaius Scribonius Curio. While at first a strong supporter of Pompey, he later quarrelled with him and went over to Caesar, whom he had previously attacked. In 54, as candidate for the consulship, he lost Caesar's support by revealing a scandalous transaction in which he and his fellow candidate had been implicated.