イーオーの神話には、さまざまな形や装飾が施されている。一般に、イーオーはアルゴスのヘライオンでヘーラーの巫女をしていた。ゼウスはイーオーに欲情し、ヘーラーはイーオーを雌牛にしてゼウスから隠したか、ゼウスがヘーラーから隠すためにイーオーを雌牛にしたが、見つかってしまった。ヘーラーはイーオーをオリーブの木につなぎ、アルガス・パノプテスに監視させたが、ゼウスはヘルメースに命じて彼を殺させた<ref name="OCD_Io">Dowden Ken, Hornblower & Spawforth, The Oxford Classical Dictionary, 1996, Oxford University Press, Oxford, isbn:019866172X, pages762–763, Third</ref>。ヘーラーは激怒し、カマドウマ(ギリシャ語の「Lang」、「発情」を意味する)を送ってイーオーを追いかけさせ、常に刺し続けさせた。イーオーはアジアに逃げ、やがてエジプトにたどり着いた。そこでゼウスは彼女を人間の姿に戻し、イーオーは彼の息子エパフォスを産んだ<ref name="OCD_Io" />。
=== Judgment of Paris パリスの審判 ==={{Main|Judgement of Paris}}[[File:Mengs, Urteil des Paris.jpg|thumb|This is one of the [[Judgement of Paris#Gallery|many works]] depicting the event. Hera is the goddess in the center, wearing the crown. ''Das Urteil des Paris'' by [[Anton Raphael Mengs]], ca. 1757]]
A prophecy stated that a son of the sea-nymph [[Thetis]], with whom Zeus fell in love after gazing upon her in the oceans off the Greek coast, would become greater than his father.<ref>Scholiast on Homer’s ''[[Iliad]]''; Hyginus, ''[[Fabulae]]'' 54; Ovid, ''[[Metamorphoses]]'' 11.217.</ref> Possibly for this reason,<ref>[[Bibliotheca (Pseudo-Apollodorus)|Apollodorus]], [https://www.perseus.tufts.edu/hopper/text?doc=Apollod.+1.1.1&redirect=true 3.168].</ref> Thetis was betrothed to an elderly human king, [[Peleus]] son of [[Aeacus]], either upon Zeus' orders,<ref>[[Pindar#Chronological order|Pindar]], ''Nemean'' 5 ep2; Pindar, ''Isthmian'' 8 str3–str5.</ref> or because she wished to please Hera, who had raised her.<ref>Hesiod, ''[[Catalogue of Women]]'' fr. 57; ''[[Cypria]]'' fr. 4.</ref> All the gods and goddesses as well as various mortals were invited to the marriage of Peleus and Thetis (the eventual parents of [[Achilles]]) and brought many gifts.<ref>Photius, ''Myrobiblion'' 190.</ref> Only Eris, goddess of discord, was not invited and was stopped at the door by Hermes, on Zeus' order. She was annoyed at this, so she threw from the door a gift of her own:<ref>[[Hyginus]], ''[[Fabulae]]'' 92.</ref> a [[golden apple]] inscribed with the word καλλίστῃ (kallistēi, "To the fairest").<ref>[[Bibliotheca (Pseudo-Apollodorus)|Apollodorus]], [https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.01.0022%3Atext%3DEpitome%3Abook%3DE%3Achapter%3D2%3Asection%3D2 E.3.2].</ref> [[Aphrodite]], Hera, and Athena all claimed to be the fairest, and thus the rightful owner of the apple.