Princess Ivy is the protagonist, then true main antagonist of The Song of the Nightingale. She is also the main antagonist of the Sofia the First special The Curse of Princess Ivy.
Ivy was a princess of Prisma, a land turned black and white by the grief and depression of its king. After being told that her older sister will be made queen, Ivy wanted to prove that she was worthy of the throne. This only resulted in the king falling prey to Professor LeFoof's mechanical bird, which drained life force from him the more he listened to its song. Ivy then set out to fix her mistake by finding the nightingale that had brought the king joy just a few days before. Ivy only seemed to get worse through the journey, and her ego grew with every challenge she overcame. After discovering she could bargain with Death to reap rewards, she bargained Professor LeFoof's soul in exchange for the power to take over Prisma. But, when she began her conquest, she fell victim to the very thing that started her on her journey in the first place: the hypnotic melody of the mechanical bird. After that, she was banished to a desert island, where I'm sure she'll neeeever bother anyone again.