Theoris of Lemnos (Ancient Greek: Θεωρίς) (died before 323 BC) was an ancient Greek woman from Lemnos who lived in Athens in the fourth century BC, and worked as a witch or folk-healer. At some point before 323, she was tried and executed along with her children. The precise details of Theoris' offence are unclear: modern scholars have variously suggested that she was convicted of intentional homicide, planning to commit homicide, or asebeia (impiety). Three ancient accounts survive of her prosecution, which constitute the most detailed account of a witch trial to survive from Classical Greece.