1. A daughter of Epimetheus and Pandora, and wife of Deucalion who together with her husband escaped the Great Deluge.
2. A daughter of King Creon of Thebes.From Smith's Dictionary of Greek and Roman Biography and Mythology
From The Theogony of Apollodorus I
And Prometheus had a son Deucalion. He reigning in the regions about Phthia, married Pyrrha, the daughter of Epimetheus and Pandora, the first woman fashioned by the gods. And when Zeus would destroy the men of the Bronze Age, Deucalion by the advice of Prometheus constructed a chest, and having stored it with provisions he embarked in it with Pyrrha. But Zeus by pouring heavy rain from heaven flooded the greater part of Greece, so that all men were destroyed, except a few who fled to the high mountains in the neighbourhood.
From Metamorphoses by Ovid. Book The First
Which when Deucalion, with a piteous look
Beheld, he wept, and thus to Pyrrha spoke:
Oh wife, oh sister, oh of all thy kind
The best, and only creature left behind,
By kindred, love, and now by dangers joyn'd;
Of multitudes, who breath'd the common air,
We two remain; a species in a pair:
The rest the seas have swallow'd; nor have we
Ev'n of this wretched life a certainty.