Thaïs or Thais (Greek: Θαΐς; flourished 4th century BC) was a famous Greek hetaira who accompanied Alexander the Great on his campaigns. Likely from Athens, she is most famous for instigating the burning of Persepolis. At the time, Thaïs was the lover of Ptolemy I Soter, one of Alexander's close companions and generals. It has been suggested that she may also have been Alexander's lover, on the basis of Athenaeus's statement that Alexander liked to "keep Thaïs with him", but this may simply mean he enjoyed her company, as she is said to have been very witty and entertaining. Athenaeus also says that after Alexander's death Ptolemy married Thaïs, who bore three of his children, and may also have become a Queen of Egypt.