He mastered the Forbidden Arts twice, with the help of magic-shaper, Clavius, and his sorceress consort, Zelda, both of whom he betrayed once they had outlived their usefulness. With these powers, he could create anything, shapeshift himself into anything, and destroy anything with a powerful blast of red energy. He wanted King William's kingdom, but was never able to take over it because his power of the Forbidden Arts was not enough for him to keep the kingdom.
Rothbart was not pleased with Odette's birth and was captured when King William knows his evil plan and was sentenced to banishment. Before he leaves, he makes a vow that he will take everything that King William loves and owns. After saying those words, he banishes for quite a long time before making an appearance again as the "Great Animal" when Odette and King William are heading back to their kingdom, killing King William in the process.
He imprisons Odette by casting her a spell that allows her to be a swan by day and a human by night and only releases her if she agreed to marry him (which Odette refuses to do so). When Rothbart finds out about the ball, he disguises Bridget as Odette and sends her to the ball so that Derek can make a vow of everlasting love to the false Odette. After saying the vow, Rothbart appears in Derek's castle and reveals that the fake Odette was actually Bridget in disguise and the real Odette is dying as the spell drains her life away.
He arrives at Swan Lake and saw Derek weeping over Odette's death. Derek forces Rothbart to bring her back to life but he refuses and only agree to do so if Derek successfully kills him and transforms into the Great Animal. Thanks to Lord Rogers's Catch and Fire technique that Derek and Bromley practiced, Derek shot Rothbart in the heart with an arrow, destroying him and reviving Odette.
Rothbart returns again as a ghost and this time, he has a plan to return from the dead, enlisting a black cat named, Number 9, to help him by promising him extra lives. Number 9 succeeds in luring Derek to the cellar of Queen Uberta's castle, where he opens a chest with the initials, R on it. There is nothing inside at first but when Derek leaves, Rothbart emerges from the chest as a ghost. From there, he moves to the next portion of his plan, that is to destroy the Christmas spirit of the kingdom, the only thing more powerful than the magic of Forbidden Arts, which will give him the power to be revived once again but in physical form.
He casts small spells that causes people to fight, which he does this to Queen Uberta and Lord Rogers before spreading it to the villagers. Derek and Odette learned about his return when the wind chimes are playing a song, "Far Longer than Forever", making him visible and holds him. They set up the chimes all around the castle but Rothbart eventually re-enlists the help of Bridget, his former minion from the first film who had turned away from his influences, and she helps to remove the wind chimes for him.
Odette invites the orphans to perform "Christmas is the Reason", which weakens Rothbart's power over Queen Uberta and Lord Rogers. Odette later invites Queen Uberta and Lord Rogers to give gifts and food to the poor. The good will breaks the spell casted on the whole kingdom and Rothbart becomes powerless. His last chance to ruin Christmas is to sabotage the royal Christmas tree by sending Number 9 to steal one of the Christmas lights from the tree and he casts a spell on it that will destroy the tree. Derek learns the plan thanks to Bridget who has double-crossed Rothbart and traps him inside a giant chime.
Derek rushes back to the Christmas Eve party to prevent the tree from being lit but was too late. Rothbart, in his physical form, takes Queen Uberta's crown and kidnaps Odette once more, taking her back to Swan Lake. He casts a spell on Odette again, changing her back into a swan and traps her inside a cage made of roots. He then casts a spell on the moonlight and when it touches Odette's wings, she will turn into a golden, swan-shaped Christmas ornament forever. Derek arrives and battles with Rothbart, who turned into the Great Animal, once more but was overpowered by Rothbart. Odette starts singing "Seasons of Love" which weakens Rothbart until he eventually bursts into flames and vanishes while Odette returns back to her human form again.
Rothbart is a slender man with red eyes, and he has a fair skin and half bald head with an orange colored hair and the two orange colored sideburns growing from each side of his face, thick orange eyebrows and a big, orange moustache. He wears a black cowl hooded cloak cape with a plum lining, a mustard dagged edge neck collar with all the yellow pearls over a blue long kurta tunic shirt, a blue long kurta tunic shirt, dark tan gauntlet gloves, a black belt with a golden buckle on a black belt around his waist on a blue long kurta tunic shirt, dark gray pants and black boots with all the dark beige dagged edge folded cuffs and all the mustard pearls over black boots. Sometimes, he wears a golden crown on his head.
- "No more Mr. Nice Guy, no sirry!" - Rothbart making an entrance in Derek's castle at the ball.
- "Once you steal something, you spend your whole life fighting to keep it."
- "If you hurry, little prince, I'll let you see her one last time..." - Rothbart talking as Derek on horseback sprints to reach a dying Odette.
- "No need to shout!" - Rothbart talking to Derek as Derek weeps for Odette's death at Swan Lake.
- "On The First Day Of Christmas Prince Derek Gave To Me A WAY BACK TO EARTH" - Rothbart emerging as a ghost
- "I Can't Cast A Spell On Derek Or Odette, They Got Too Much Christmas Spirit"
- "Only if you defeat me." his last and final words before he turns and transforms into the great animal ?!
- Even though he dies, he appears in every film and has a key role in each and every one. The only ones he doesn't appear in is the sixth and seventh films.
- In the original ballet, his full name was Von Rothbart.
- He also had a daughter named Odile, who resembled Odette and shared some of his magical powers - however, in some productions, she is identified as Odette's evil twin sister or simply a magically created doppelgänger.
- When he shape-shifted, he took on the form of a giant owl or a grotesque reptilian humanoid, not a bat-like wyvern as depicted in the film franchise
- It is also worth mentioning that his reasoning for kidnapping Odette is different than that of the movies, his purpose in doing so is never specified, whereas the films dictate that he kidnapped Odette in order to force her into marriage.
- It is also mentioned in the ballet that he had kidnapped numerous maidens and placed them under similar curses, these "swan maidens" treated Odette as their queen while in Rothbart's captivity.
- In some adaptations of the ballet - namely the original - Rothbart triumphs and Derek (known as Siegfried in the ballet) and Odette perish, having failed in their attempt to break the curse. Other variations would have him killed in a battle against Derek (which is the ending the film followed) or simply rendered powerless after the couple breaks the spell. In one adaptation, Rothbart kills Derek and elopes with Odette, while another would have both him and Derek killed in combat, leaving Odette alone and grief-stricken, still trapped in swan form.
- The bonus features from the original film features a 'read-a-long' version of the movie. In the storybook read-a-long Rothbart is referred to as Odette's uncle. So this would imply incest if Rothbart's goal was to marry Odette.
- Rothbart is the first Swan Princess character to come back as a ghost, the second character being Scully during the end of A Royal Family and Princess Tomorrow, Pirate Today.