Ursula (The Little Mermaid)

Ursula, also known as the Sea Witch, is a character on Disney's The Little Mermaid franchise. Ursula is usually depicted as having octopus legs, but she has appeared twice as a mermaid: in the book Reflections of Arsulu, and in the TV-series Once Upon a Time. In the tv series, she is portrayed by Tiffany Boone in her younger mermaid form.

Biography
Ursula is the sea with who granted Ariel her legs in exchange of her voice. Ursule then used the stolen voice to trick Prince Eric into marring her, but she was defeated by Triton.

The Little Mermaid
Ursula is the villain in the movie and is killed in the end.

The Little Mermaid (TV series)
Ursula appears as the main villain of the Little Mermaid prequel television series, (which takes place one year prior to her death in the original film).

Printed Media
Everyone at the palace thinks Adella's new best friend, Arsulu, is wonderful. But Ariel has her doubts. Why is it, she wonders, that ever since Arsulu came to stay with them at the palace, strange and terrible things have been happening?

A suspicious Ariel decides to spy on Arsulu to see if she's really to blame. That's when she learns the horrible truth about Arsulu, she is in fact Ursula in disguise. But how can Ariel convince her sisters that their dear, sweet guest is really a danger to them all?

Once Upon a Time
Ursula was born to King Poseidon and his unnamed wife, Ursula is named after a sea goddess of the same name. As a child, she is taught to sing from her mother, who used to sing at Glowerhaven. After her mother is killed by a pirate, Poseidon holds a grudge against humans, and he makes his daughter lure sailors at sea to their doom with her singing voice. Ursula complies, nearly killing the crew aboard the Jolly Roger, but she lets them go at the last moment. While Poseidon is disappointed in her actions, she argues that her singing is the only memento of her mother, and doesn't wish to use her gift to harm others. At her insistence that not all humans are bad, he orders her to obey his wishes as long as she lives in his kingdom. She rebels, stealing a magic bracelet from his vault, which gives her human legs. With plans of going to Glowerhaven, she begins singing at a pub to earn gold for the trip. After Ursula captivates an audience with her voice, Hook, captain of the Jolly Roger, befriends her and offers to take her to Glowerhaven. However, she later learns from Hook that her father asked him to trap her singing voice within an enchanted shell in exchange for squid ink, which he desires for vengeance against an evil man. Instead, Ursula steals the ink from Poseidon's vault for him just as her father arrives to take the procured item away. Angered that his only hope of revenge has been crushed, Hook removes Ursula's singing voice so Poseidon can never use his daughter to sink another ship again. Shattered at this betrayal, Ursula decides she no longer wants to be a mermaid and uses her father's trident to transform her tail into tentacles.

Link

 * Ursula's Page on Once Upon a Time wiki
 * Ursula 's page on the Disney Wikia