| Captain Hook |
| Caroline Ford |
Nimue convinces Captain Hook to crush the heart of Merlin, the thing she loves the most, in order to start the Dark Curse. Because she lives is all Dark Ones, when Hook crushes the heart, it means she will, too. They succeed and the Dark Curse is enacted, as Merlin dies.
Later, Hook and the vision of Rumplestiltskin are at the lake, where they open the portal to the Underworld and resurrect Nimue and the other Dark Ones, who intend to snuff out the light.
Nimue is the leader of the Dark One invasion in Storybrooke. Part of their plan is to trade places with someone in the living world and have that person take their place in the Underworld. Nimue marks Henry. When Emma Swan tries to interfere with their plot, Nimue sends Captain Hook to stop her, and makes her way over to Granny's, where Snow, David and Henry are all having dinner. She uses her magic to transport them to the pond where the Underworld portal lays, and she and the other Dark Ones prepare to take their lives. Emma shows up and attempts to stop them, but Nimue begins to magically harm her to stop her from interfering. Upon seeing this, Hook is unable to go through with the plan and uses Excalibur to exhume the Darkness from Nimue and the others and suck them all into the sword.
- Nimue is based on Nimue from Arthurian legend.
- Nimue is one of three main antagonists for Season 5A, along with Emma Swan and Captain Hook. She is the final, and arguably true, antagonist, being the one who was manipulating most of the events.
- Nimue lives inside all Dark Ones.
- Nimue has the shortest episode count of the main antagonists in the series, only appearing four times.
- Nimue is possibly the person taunting Emma as Rumplestiltskin and the other Dark Ones, implied when he shifts into her in "Broken Heart". However, she mentions in "Nimue" that she is able to view things through the Rumplestilskin vision Emma sees.