Euryale

Euryale is a Gorgon sister of Medusa and Stheno. Despite having faded earlier, Gaea revived her at some point. She appears in The Son of Neptune.

The Son of Neptune
She, along with her sister Stheno, had been repeatedly killed by Percy Jackson, but they just kept on reforming. She scolds her sister for telling Percy the secret of Gorgon blood and for being too obsessed with her work, her hair is all coral snakes.