Nereids (Neh-ré-id) or 'River Dryads' are a rare type of fish-like people that, as per the name, live in rivers and lakes. Each river typically only has one native Nereid, who guards it like a parent would their child. Popular fairy tales paint them as child-stealing witches, but as Knife the Goblin and his friends find out during one adventure, this couldn't be further from the truth.

Pictured here is a specific Nereid, nicknamed 'Nyssa' by the gang after the river they inhabit (Nys Creek). The bottle on their staff is full of water from their river; much like a Dryad can't stray far from their tree, a Nereid can't roam far from their river. However, if Nyssa carries a bit of it with them, they can roam more freely.