Spoilers if you haven't seen the last few episodes of Once Upon A Time.
- You're looking for the Wicked Witch of the West.
- There's a mysterious new woman in town that no one knows and who wears a large green necklace.
But no one can connect those two dots and at least be suspicious of her. At least now they know Zelena is the Wicked Witch (but not from figuring it out on their own).