King William is Odette's father who appears in the beginning of the first film. He devised a plan with the ruler of the neighbouring kingdom, Queen Uberta, to marry off their children, Derek and Odette. Shortly after Odette's birth, he defeated the sorcerer Rothbart and banished him, instead of imprisoning him or executing him.
DeathEditHe dies when Rothbart attacks him and his guards when they left Derek's Kingdom, and kidnaps Odette. After upon hearing this, Derek arrives and sees William laying on the ground, telling him that "it's not what it seems..." before dying. With William gone, his Kingdom is now Odette's and that is what Rothbart wants.
- King William is voiced by American actor Dakin Matthews.
- King William appears in a flashback from the 5th movie. This actually was a deleted scene from the first film.
- In The Swan Princess Christmas, Odette said that she and King William used to go to the woodcutters village every Christmas leaving food and presents at their doorsteps. This is the first time he's been used in a sequel.
- In The Swan Princess: Royally Undercover King Williams is given a lot of buildup. While he didn't like to talk about war he risked his life for others who fought alongside him including the King of Trumbeau
- King William's last words before dying is similar to when Littlefoot's mother dies in The Land Before Time.