Timaeus of Locri (Ancient Greek: Τίμαιος ὁ Λοκρός; Latin: Timaeus Locrus) was a Greek Pythagorean philosopher living in the 5th century BC.
He features in Plato's Timaeus, where he is said to come from Locri in Italy, thus of Locrian origin.
He also appears as one of the speakers in Plato's Critias.
Later references to Timaeus of Locri from Antiquity are by:
* Cicero, in his De re publica (I, X, 16), where he is described as an intimate of Plato
* Proclus, in his Commentary on Plato's Timaeus (II, 38, I)
* Simplicius and Diogenes Laertius, in their descriptions of, and commentaries on Aristotle's work
All ancient references to him seem to have derived from Plato: he may well be a fictional character invented for the dialogue bearing his name (see M. F. Burnyeat).
Of Locri, in Italy, a Pythagorean philosopher, is said to have been a teacher of Plato. He gives his name to a dialogue of Plato, in which is given the account of the mythical island Atlantis, lying in the Western Ocean, and supposed by many in modern times to have been suggested by vague stories of the American continent.