Athenian courtesan who traveled with the army of Alexander the Great in its invasion of Persia. She is chiefly known from the story that represents her as having persuaded Alexander to set fire to the Achaemenian capital of Persepolis in the course of a drunken revel. The authenticity of this anecdote, which forms the subject of John Dryden's Alexander's Feast (1697), is doubtful, since it is based upon the authority of Cleitarchus, one of the least trustworthy of the historians of Alexander. Persepolis was probably set afire for political reasons.

Courtesans in Greek and Roman comedy were often named Thais. There is also a Christian saint called Thais, a reformed prostitute, but her story is probably fictitious; it was used by Anatole France for his Thaïs (1890) and thence for Jules Massenet's opera of the same name (1894).