Achlys (Ancient Greek: Ἀχλύς "mist"), in the Hesiodic Shield of Heracles, is one of the figures depicted on Heracles' shield, perhaps representing the personification of sorrow. In Homer, achlys is the mist which fogs or blinds mortal eyes (often in death). Her Roman counterpart Caligo was said to have been the mother of Chaos. In Nonnus's Dionysiaca, she seems to be a witch.