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Every time I heard you sing, I heard your mother, and it was too painful. I let that pain fuel my desire for vengeance, but it shouldn't have. It should have reminded me that I still had a piece of her. You.
—Poseidon to Ursula src

King Poseidon, also known as the Sea King, is a character on ABC's Once Upon a Time. He débuts, with his only appearance, in the fifteenth episode of the fourth season and is portrayed by guest star Ernie Hudson.

Poseidon is based on the god of the same name from Greek Mythology, the mermaid's father from the fairytale "The Little Mermaid", and King Triton from the Disney film, The Little Mermaid.


Before First Curse

Poseidon reigns as the sea king. With his unnamed wife, he has a daughter, Ursula, who is named after the sea goddess of the same name. His wife and daughter, both renowned for their singing voices, give him much happiness. However, when his wife is killed by a pirate, Poseidon comes to hate humans and has Ursula lure sailors to their deaths with her enchanting voice. During one such excursion, she allows the crew aboard the Jolly Roger to live and incurs her father's disappointment. Longing to instead honor her mother's memory, Ursula doesn't wish to use her singing talent to harm others and insists all humans can't bad, but Poseidon commands her to obey him as long as she lives in his kingdom. Upset at his demands, she steals a magic bracelet from his vault to gain human legs and disappears with plans of going to Glowerhaven to become a singer. Once Poseidon discovers Hook, captain of the Jolly Roger, has agreed to take Ursula there, he offers squid ink, which the pirate can use to give retribution to the Dark One. In return for this much-needed item, the sea king enchants a shell and asks him to trap his daughter's voice within it so she won't leave the kingdom for Glowerhaven. Instead, Hook tells Ursula about the deal, and she procures the ink from her father's vault for him. Poseidon accosts them, and as Ursula sides with Hook, he takes away the ink to prove the pirate only cares about his vengeance. As expected, Hook is furious that his only hope of getting revenge is gone, and he gets back at Poseidon by absorbing Ursula's singing voice so the sea king can never sink another ship again. Under Hook's threats, Poseidon is forced to retreat without regaining the shell. Later, Ursula uses her father's trident to transform her mermaid fin into tentacles to become more powerful than him. ("Poor Unfortunate Soul")

After Second Curse

With Ariel's help, Poseidon travels to Storybrooke to meet with Ursula, who is now a grown woman. As the person who originally enchanted the shell, only he can restore Ursula's voice, which she desires to regain. During their reunion, Poseidon apologizes to his daughter for using her gift for horrible deeds and expresses regret for not cherishing her talent as a happy reminder of his late wife. After restoring her voice, he turns to leave, but a moved Ursula wishes to reconnect and decides to go home with him. ("Poor Unfortunate Soul")

Magical Abilities

  • Teleportation - Ability to magically teleport oneself and/or others from one location to another.


Character Notes

Production Notes

  • He is described as, "a king whose crown was hard-won, and the fight to keep it has taken a toll", but also as "handsome, though not refined, and highly protective of his family".[1]

Prop Notes

Costume Notes

  • Poseidon costume was originally different, and included a big purple feathery boa around his neck. However, it didn't look quite right, and they ended up with a more metallic version of the original costume.[4] ("Poor Unfortunate Soul")


See also


  1. Mitovich, Matt Webb (December 3, 2014). Matt's Inside Line: Scoop on Once, Arrow, H50, Vampire Diaries, Scorpion, SVU, PLL, Mentalist, Haven and More. TVLine. “Bonus Scoop: For Episode 15, Once is casting the possibly recurring role of a king whose crown was hard-won, and the fight to keep it has taken a toll. He is also described as "handsome, though not refined, and highly protective of his family."”
  2. File:415YourMotherWanted.png
  3. "Poseidon" trident from Once Upon a Time Season 4, Episode 16.. iCollector. Retrieved on November 30, 2018.
  4. Steve Pearlman on the Season One Blu-ray Audio Commentary for "Poor Unfortunate Soul"

Start a Discussion Discussions about Poseidon

  • Deity infoboxes

    4 messages
    • Lady Junky wrote: I disagree. Doing that would mean that we're assuming all gods originate from Mount Olympus. And that's speculatio...
    • NickM98 wrote: Lady Junky wrote: I disagree. Doing that would mean that we're assuming all gods originate from Mount Olympus. And that...
  • Is Poseidon Hades' brother?

    8 messages
    • Lady Junky wrote: CoolDudeAl wrote:We don't know yet. We also don't know if Hercules is going to be Zeus's son, although...
    • Frieza1500 wrote:In Greek Mythology, Hades, Zeus, and Poseidon are all brothers. All of the Greek gods are siblings, and some of even marr...