In Greek mythology, Ischys (Ancient Greek: Ἰσχύς, "strength") was the son of Elatus. He is remembered chiefly as the mortal lover of Coronis, a Thessalian princess who was already carrying the unborn child of Apollo (the future Asclepius) when she took up with him. When the affair was revealed, Coronis was killed and Ischys was slain — by Apollo's father Zeus or by Apollo himself. He is also known under the alternative names Alcyoneus and Lycus.
Adapted from Wikipedia, "Ischys" · CC BY-SA 4.0
I.Family
Ischys was the son of Elatus. He belongs to the Arcadian house descended from Arcas, where Elatus is counted among the sons of Apheidas, son of Arcas.
In genealogies that place him here, Ischys is named alongside his brothers — among the sons of Elatus appear Aepytus, Pereus, Cyllen, Ischys and Stymphalus — several of whom gave their names to Arcadian places.
II.Mythology
Ischys engaged in an affair with Coronis, a Thessalian princess and one of Apollo's lovers, while she was carrying Apollo's unborn child.
When a then-white raven told Apollo of the affair between Ischys and Coronis, the god became so angry that his glare scorched the raven black — explaining how the bird came to have its dark plumage.
Apollo's twin sister Artemis killed Coronis as a punishment for the insult, but the unborn child was saved and rescued at the last moment; this child was Asclepius, who would become the god of medicine.
III.Death
Ischys was then killed for the affair. The accounts disagree on the slayer: he was struck down by Apollo's father Zeus, or else by Apollo himself.
The episode of Coronis and Ischys is attested by ancient authors including Pindar, Apollodorus, Pausanias and Hyginus.
IV.Alternative names
The mortal lover of Coronis was not always called Ischys. He is also known as Alcyoneus, a name given by Antoninus Liberalis.
In the commentary of Lactantius Placidus on Statius, the same figure appears under the name Lycus.