Gaius the Platonist (2nd century) was a Greek or Roman philosopher, and a representative of Middle Platonism. Very little is known about him except that he was the teacher of Albinus, who is known to have published a now lost nine-volume summary of Gaius' lectures on Plato.[1] He taught Platonism in the first half of the 2nd century,[2] but almost nothing is known about his philosophical opinions.[3] It has been speculated that the On Plato and His Doctrine written by Apuleius may have been taken from the lectures of Gaius, but this assertion is now seen as dubious.[4] It has also been thought that the anonymous commentary on the Theaetetus of Plato, which is partially extant, may have come from his school.[5] Porphyry mentions that his works were read in the school of Plotinus.[6]