Enchanted Forest Character
Biographical Information


Physical Description




Hair color


Eye color


Current Allies
Current allies:
Portrayed By

Ernie Hudson

First mentioned


Appears in

"Poor Unfortunate Soul"

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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

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. He is portrayed by guest star Ernie Hudson.

Poseidon is based on the god of the same name from Greek Mythology, and is an allusion to 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 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")


Character Notes

  • The name "Poseidon" may be derived from the Greek words "posis" and "de" that respectively mean "husband, lord" and "earth".[1]
    • His name is also the same as famed Greek god, who controls the sea and earthquakes and is also the brother of Zeus.[1]
  • Anna and Elsa's parents died in a shipwreck near his territory. ("Fall")

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".[2]