Siren

"Some illusions are better than truth."

- The Siren to Prince Charming

The Siren was a character on Once Upon a Time. She made her début, and only appearance, in the thirteenth episode of the first season. She was portrayed by guest star Aria Pullman (in her true form) and Ginnifer Goodwin (in her disguised form). She does not have a Storybrooke counterpart.

History
She guards the waters of Lake Nostros, whose magic waters are said to return something once lost. Prince Charming faces the Siren while trying to get water for Princess Abigail. She tries to seduce him but fails, so she takes the appearance of the person he longs for, Snow White.

She manages to kiss Prince Charming, but he is still immune to her effects knowing it is not true love. The Siren admits he is the first person to realize that and then tries to drown Prince Charming. While underwater, she kisses him again, but he stabs her with a knife and she dies, allowing him to collect the water. ("What Happened to Frederick")

When Prince Charming returns to Lake Nostros in order to heal his mother after she had been shot by a stray arrow, he finds that the lake had dried up due to the Siren's death. {"Lady of the Lake")

Trivia

 * The story of the Siren comes from Greek Mythology. In The Odyssey by Homer, and the story of Jason and the Argonauts, Sirens were woman capable of killing men simply by singing. This singing would draw sailors and their ships to their deaths crashing on the rocks surrounding the Sirens' island, and the Sirens would then devour them.
 * The Siren is the second allusion to Greek Mythology made. The first being the story of King Midas.
 * Lancelot's visit to the dried up lake may indicate the Siren may be based of the Lady of the Lake from Arthurian-lore.

Appearances
Sirene