(Θαΐς), a celebrated Athenian Hetaera, who accompanied Alexander the Great on his expedition into Asia, or at least was present on various occasions during that period. Her name is best known from the story of her having stimulated the conqueror during a great festival at Persepolis, to set fire to the palace of the Persian kings: but this anecdote, immortalized as it has been by Dryden's famous ode, appears to rest on the sole authority of Cleitarchus, one of the least trustworthy of the historians of Alexander, and is in all probability a mere fable (Cleitarchus, apud Athen. xiii. p. 576e; Diod. 17.72; Plut. Alex. 38 ; Curt. 5.7. §§ 3_7; Droysen, Gesch. Alex. p. 247, note.)

After the death of Alexander, Thais attached herself to Ptolemy Lagi, by whom she became the mother of two sons, Leontiscus and Lagus, and of a daughter, Eirene. The statement of Athenaeus that she was actually married to the Egyptian king may be doubted, but he seems to have been warmly attached to her, and brought up their common children in almost princely style. (Athen. 13.576e.) Many anecdotes are recorded of her wit and readiness in repartee, for which she seems to have been as distinguished as for her beauty. (Id. ib. p. 585.)