The Raven is the secondary main antagonist of the anime Princess Tutu.
History
The Raven was originally the main antagonist of The Prince and the Raven, a fairytale written by Drosselmeyer, who could affect reality by writting stories. However, after he was executed, the story remained unfinished, so the Raven and his rival, Prince Siegfried, escaped the story to continue their battle.
Siegfried fought bravely, but he could not stand against the Raven and his swarm of crows. In despration, the prince cast a magic spell to seal the Raven away by shattering his pure heart. The spell succeeded, but Siegfried lost his memories, and could no longer experience emotions, pain or think for himself.
In his trapped state, the Raven knew that only by consuming a pure heart could he return to his true power, so schemed up a plan to secure such a heart, this time, with something he had stolen during the swarm of crows: a baby girl he named Kraehe. For years, he had Kraehe drink his blood to give her his powers. She truly believed that she was his daughter, but had somehow been born into a human's body.
One day, while still very young, Kraehe met and fell in love with what remained of Prince Siegfried: a orphan named Mytho. When his daughter told him about this meeting, the Raven told her that she should make him fall in love with her, as only the prince, who loved all living creatures, could love her, when he really wanted her to make the prince turn to their side. Years past, and Kraehe continued to try and make Mytho love her, even going to attend a ballet class at the town's academy with him as a girl named Rue.
When Drosselmeyer finally decided to resume his story from beyond the grave, he gave a duckling the power to become a fabled ballerina named Princess Tutu to collect the shards of Siegfried's heart. Kraehe tried to stop Tutu, but turned to the Raven for help when all else failed. He had his daughter soak the shard containing the emotion of love in his blood, then give it to Mytho, causing him to turn into the cruel and devious Prince of Crows. After this, the hunt for pure hearts began, but Tutu managed to thwart all attempts.
After some unwitting help from a magic puppet named Uzura, Kraehe was able to see the truth about her birth, that she was a kidnapped human, not a raven, and began to doubt what she was doing, causing her to lose the power to be Kraehe, and stay as Rue. When Tutu secured the rest of the heart shards, the ones that sealed the Raven away, the Raven was finally set free, and planned to eat the heart of the prince. Rue, powerless and desperate, professed her love for Mytho. This caught the Raven's attention, and decided to consume Rue instead.
Realizing that Rue was his true love, Mytho asked that Tutu help him defeat the Raven once and for all. Tutu sacrificed her power to make Mytho into Siegfried, and so became an ordinary duckling again. Siegfried saved Rue, and the duckling and Fakir, the great-great-great grandson of Drosselmeyer who had inherited the power to write fate-changing stories, inspired hope inside the people. Against the overwheming hope and love, the Raven was finally killed.