Nyssa Barrera

Nyssa (Νύσσης in Ancient Greek) is a daughter of Hephaestus.

The Lost Hero
Nyssa is temporary head counselor while Jake Mason is injured. Nyssa was first seen when Leo arrived at the forge in Camp Half-Blood and explains to him about the curse that's been plaguing their cabin and how they lost the dragon. She was later seen when Leo comes back from his quest and was one of the people to cheer Leo becoming the senior counselor of the cabin.

Appearance
Leo describes her saying she looked like "one of those female action heroes, except for that smiley face band-aid on her chin." She is described as wearing a tank top and a bandanna to tie back her dark hair.

Trivia

 * She's the only daughter of Hephaestus mentioned in both series.