Socrates, who is the narrator. Glaucon. Adeimantus. Polemarchus. Cephalus. Thrasymachus. Cleitophon. And others who are mute auditors.
The scene is laid in the house of Cephalus at the Piraeus; and the whole dialogue is narrated by Socrates the day after it actually took place to Timaeus, Hermocrates, Critias, and a nameless person, who are introduced in the Timaeus.