Princess Ivy

Princess Ivy is the main antagonist of the Sofia the First special The Curse of Princess Ivy, voiced by Anna Camp.

Background
Ivy was once a princess of a far away black and white kingdom who became jealous of her older sister becoming queen. When she tried to overthrow her sister to gain the crown, she was caught, and marooned on a deserted island, where she was imprisoned for a decade.

Unfortunately, this would not be the last time anyone would hear of her. When Amber found out about Sofia's amulet, she jealously took it without her permission, so she could have a turn. Taking Sofia's amulet and betraying her trust counted as a bad deed, and the amulet put a curse on Amber by summoning Ivy and setting her free. Now free from her isolated prison, she plans to claim the Kingdom of Enchancia as her own by overthrowing King Roland and turning the whole land black and white to suit her taste.

Trivia

 * She shares the same hair color as other villains, most closely resembling Cruella De Vil from One Hundred and One Dalmatians. Ivy also share the same name as Cruella's niece, Ivy De Vil, from 101 Dalmatians: The Series.
 * The hair color scheme is also commonly used by other villains, such as Cedric the Sorcerer and the evil Alex Russo from The Wizards Return: Alex vs. Alex. The future counterpart of Shego from Kim Possible: A Sitch in Time has a similar white streak in her black hair.
 * Princess Ivy's voice is performed by Pitch Perfect and former True Blood star Anna Camp.
 * She is the first princess summoned by the amulet that is not a Disney Princess and is also not here to help.
 * She is the second princess, not of the Disney Princess line-up, that is not a child and is much older than a preteen, to appear on Sofia the First. The first is Cora from Sofia the First: The Floating Palace.
 * She is the first villain in the series to try and destroy the Amulet of Avalor instead of stealing it for its power, unlike Cedric and Miss Nettle. This was because she was summoned by the Amulet; if the Amulet is not destroyed, she will be sent back to her prison and stay there forever.
 * She's also very similar to Chick Hicks, Turbo, and Mor'du: She's a villain who became evil because of jealousy and hubris, She tried to take over a place through a hostile takeover. She's also the same kind of foil for Amber that Chick Hicks, Turbo, and Mor'du were to Lightning McQueen, Wreck-It Ralph, and Merida respectfully: A villain that helps them become a better person by embodying an evil they will become if they don't change due to having similar personalities and back stories.
 * She is the first evil princess to appear on the show (second if you include Sofia's evil copy, Sofia the Worst).
 * Ivy is the first princess to be shown how she was summoned by the amulet.