In Greek mythology, the Oreads, or Orestiads, were the nymphs that inhabited mountains, valleys, and ravines, and were sometimes associated with the goddess Artemis. They were often classified from where they dwelled; for example, the Idaeae lived in Mt. Ida, while the Peliades were from Mt. Pelion.
While searching for supplies to repair the Argo II, Leo Valdez and Hazel Levesque meet Echo and several other Oreads who are all obsessed with Narcissus. When the two demigods steal Narcissus' bronze mirror, they are stirred into a frenzy and give chase.