Timaeus is the title of one of the two Dialogues of Plato, in which we encounter the first clear reference to Atlantis and the dialogue is named after one of the participants. The dialogue is apparently a continuation of The Republic.

Some claim that Timaeus is the only character used by Plato that does not appear to have actually existed in ancient Greece. However, it is more generally accepted that the Timaeus in the Dialogues was based on a real astronomer and mathematician known as Timaeus of Locri, who was a Pythagorean philosopher who formed his own Pythagorean School in Locri in Southern Italy when the School in Croton was forced to close. Timaeus is said to have been around 70 at the time that the Dialogues were written.

Timaeus of Taormina who was born about 20 years before Plato died is not the Timaeus referred to in the Dialogue of the same name. This Timaeus was a noted historian who among others was heavily relied on by Diodorus Siculus.