Plato 
Critias 

Critias, one of Plato’s late dialogues, contains the story of the mighty island kingdom Atlantis and its attempt to conquer Athens, which failed due to the ordered society of the Athenians. Critias is the second of a projected trilogy of dialogues, preceded by Timaeus and followed by Hermocrates. The latter was possibly never written and Critias was left incomplete. Because of their resemblance (e.g. in terms of persons appearing), modern classicists occasionally combine both Timaeus and Critias as Timaeus-Critias.