Creusa is the biological mother of Ion and princess of Athens. Her father is King Erechtheus, and she is the only surviving daughter of the royal family. Thus, Creusa procuring a child concerns the entire Athenian citizenry. Creusa’s husband is Xuthus, to whom she was given as a token of Athens’s appreciation for Xuthus’s bravery in battle against the Eubeoans. Creusa was raped by Apollo in a cave in Athens when she was a young girl (many years before the timeline of the play). She exposed the infant child with a few identifying accoutrements, though she realizes that he likely died as an infant. The plot commences as Creusa and Xuthus travel to the oracle at Delphi, about 100 miles from Athens.

Creusa is often shown lamenting her fate or alluding to (without disclosing) her victimization at the hands of Apollo. Creusa believes she is childless, which, coupled with Ion’s ignorance of his parentage, supplies the central dramatic irony of the plot. Creusa denounces the liberties that gods take, especially with mortal women. Near the climax of the play, Creusa publicly scorns Apollo himself. Thus, she is a highly developed protagonist who is given special depth.