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. She worked as a witch or folk-healer. At some point before 323, she was tried and executed along with her children, though the precise details of her offence are unclear. Three ancient accounts survive of her prosecution, which constituted the most detailed account of a witch trial to survive from Classical Greece.