Creusa was the youngest daughter of Erechtheus, King of Athens and his wife, Praxithea, daughter of Phrasimus and Diogeneia. She was the sister of Protogeneia, Pandora, Procris, Oreithyia, Chthonia, Cecrops, Pandorus and Metion. Her other possible siblings were Merope, Orneus, Thespius, Eupalamus and Sicyon.
Apollodorus mentions Creusa as the mother of Achaeus and Ion by her husband Xuthus; she is presumably also the mother of Xuthus' daughter Diomede. However, according to Euripides' Ion, in which she is a prominent character, Creusa was mother of Ion by Apollo, while Xuthus was infertile so he accepted Ion as his own son. Creusa is also mentioned as the mother of Ion with Apollo by Stephanus of Byzantium. Hyginus calls Creusa mother of Cephalus by Hermes.
Creusa was spared of the fate of her sisters because she was an infant at the time they had sworn to commit suicide if one of them died. According to the general tradition, Creusa had Ion, Achaeus and Dorus by Xuthus.
But in the play Ion, Creusa was impregnated by Apollo long before her marriage to Xuthus. To protect her from her father's anger, Apollo used his powers to keep her pregnancy hidden. Creusa gave birth to her child without pain due to Apollo's intervention, but she left the baby in a cave because she feared her father's reproach. However, Apollo had Hermes bring his son, Ion, to his temple and made arrangements for him to be brought up there. Creusa, unaware of this went back to bring the child after feeling guilty. When she couldn't find the child, she assumed that the wild beasts had eaten the baby and went back grieving.
Years later, Xuthus went to consult the Delphian oracle about his marriage to Creusa being childless and met Ion, who had been raised at the temple of Apollo. The prophecy given by Apollo seemed to indicate Ion as his son, so Xuthus decided to adopt the youth. Creusa, unaware of her husband's infertility, thought that Ion's birth must have been the result of Xuthus' adultery in the past, and attempted to poison the young man, but Ion was in time to discover her conspiracy, and chased her to kill her. Creusa sought shelter at Apollo's altar and demanded not to kill her. Eventually, due to the intervention of Pythia who told to Ion that he was found abandoned and gave him the basket in which she had found him, Creusa realized that Ion was her son by Apollo she had abandoned, after Ion described to her the contents of the basket he had been found in as a baby. In the end of the play, Athena promised that Creusa and Xuthus would have two sons together, Achaeus and Dorus. The goddess then told them to keep all of this a secret from Xuthus.
- Apollodorus, 3.15.1
- Suda s.v. Maidens, Virgins (Παρθένοι)
- Apollodorus, 3.15.1.
- Plutarch, Theseus 19.5
- Pausanias, Graeciae Descriptio 2.25.6; Plutarch, Theseus 32.1; Stephanus of Byzantium, Ethnica s.v. Orneiai
- Diodorus Siculus, Bibliotheca historica 4.29.2
- Diodorus Siculus, Bibliotheca historica 4.76.1
- Pausanias, Graeciae Descriptio 2.6.5, citing Hesiod (Ehoiai fr. 224) for Erechtheus
- Apollodorus, 1.7.3
- Apollodorus, 1.9.4
- Stephanus of Byzantium s. v. Iōnia
- Hyginus, Fabulae 160
- Euripides, Ion 277
- Euripides, Ion passim
- Apollodorus, The Library with an English Translation by Sir James George Frazer, F.B.A., F.R.S. in 2 Volumes, Cambridge, MA, Harvard University Press; London, William Heinemann Ltd. 1921. ISBN 0-674-99135-4. Online version at the Perseus Digital Library. Greek text available from the same website.
- Diodorus Siculus, The Library of History translated by Charles Henry Oldfather. Twelve volumes. Loeb Classical Library. Cambridge, Massachusetts: Harvard University Press; London: William Heinemann, Ltd. 1989. Vol. 3. Books 4.59–8. Online version at Bill Thayer's Web Site
- Diodorus Siculus, Bibliotheca Historica. Vol 1-2. Immanel Bekker. Ludwig Dindorf. Friedrich Vogel. in aedibus B. G. Teubneri. Leipzig. 1888-1890. Greek text available at the Perseus Digital Library.
- Euripides, The Complete Greek Drama, edited by Whitney J. Oates and Eugene O'Neill, Jr. in two volumes. 1. Ion, translated by Robert Potter. New York. Random House. 1938. Online version at the Perseus Digital Library.
- Euripides, Euripidis Fabulae. vol. 2. Gilbert Murray. Oxford. Clarendon Press, Oxford. 1913. Greek text available at the Perseus Digital Library.
- Gaius Julius Hyginus, Fabulae from The Myths of Hyginus translated and edited by Mary Grant. University of Kansas Publications in Humanistic Studies. Online version at the Topos Text Project.
- Lucius Mestrius Plutarchus, Lives with an English Translation by Bernadotte Perrin. Cambridge, MA. Harvard University Press. London. William Heinemann Ltd. 1914. 1. Online version at the Perseus Digital Library. Greek text available from the same website.
- Pausanias, Description of Greece with an English Translation by W.H.S. Jones, Litt.D., and H.A. Ormerod, M.A., in 4 Volumes. Cambridge, MA, Harvard University Press; London, William Heinemann Ltd. 1918. ISBN 0-674-99328-4. Online version at the Perseus Digital Library
- Pausanias, Graeciae Descriptio. 3 vols. Leipzig, Teubner. 1903. Greek text available at the Perseus Digital Library.
- Stephanus of Byzantium, Stephani Byzantii Ethnicorum quae supersunt, edited by August Meineike (1790-1870), published 1849. A few entries from this important ancient handbook of place names have been translated by Brady Kiesling. Online version at the Topos Text Project.
- Suida, Suda Encyclopedia translated by Ross Scaife, David Whitehead, William Hutton, Catharine Roth, Jennifer Benedict, Gregory Hays, Malcolm Heath Sean M. Redmond, Nicholas Fincher, Patrick Rourke, Elizabeth Vandiver, Raphael Finkel, Frederick Williams, Carl Widstrand, Robert Dyer, Joseph L. Rife, Oliver Phillips and many others. Online version at the Topos Text Project.