In the animated film Howl's Moving Castle, the character known as Bruxa, or the Witch of the Waste, serves as a primary antagonist whose power and personal history drive much of the story's conflict. Her background is that of a once-renowned and immensely powerful sorceress who was banished to the desolate Wastelands by the king fifty years before the events of the film. This exile was a direct consequence of her dangerous ambition and formidable abilities, which the kingdom saw as a threat. Long before her banishment, she had a close relationship with the wizard Howl, acting as his teacher and a significant figure in his life, but her obsession with him eventually transformed into a possessive and toxic form of love. When Howl rejected her, she cursed him, vowing that he would return to her whenever he fell in love.

In terms of personality, the Witch of the Waste initially presents as a figure of immense vanity, jealousy, and spitefulness. Her motivation is deeply rooted in her unrequited obsession with Howl; she desires to possess his heart and will go to great lengths to eliminate any rival for his affection. This is most clearly demonstrated when she spots Sophie with Howl and, consumed with jealousy, curses the young hat maker, transforming her into an old woman. Her role in the story is that of the catalyst for the main plot, as her curse forces Sophie to leave her home and seek a way to break the spell, eventually leading her to Howl's moving castle. She also serves as a persistent threat, representing the destructive nature of unchecked envy and the consequences of clinging to a lost past.

Her key relationships are central to understanding her character. Her relationship with Howl is the core of her identity as an antagonist; she is a spurned former lover and a dangerous pursuer who wants to reclaim him by force. Her relationship with Sophie is that of a rival and a target. By cursing Sophie, she inadvertently sets in motion the very events that will bring Sophie and Howl closer together. The Witch of the Waste also serves as a dark mirror to Sophie. Both characters undergo a significant transformation linked to age and appearance. While Sophie is cursed to look old but remains young at heart, the Witch of the Waste is implied to be truly old but uses magic to maintain a youthful facade. Their trajectories are opposites: Sophie grows in confidence and self-acceptance, while the Witch's power and identity crumble.

The character undergoes a notable development. Her immense magical power is ultimately stripped away by Howl's former mentor, Madame Suliman, as punishment for her crimes. This loss is a pivotal moment, as she is reduced to a frail, elderly woman who can no longer sustain her vengeful pursuits. In this weakened and helpless state, she is taken in by Sophie, who shows her compassion. This marks a profound shift from enemy to a dependent figure. In the film's climax, the Witch, still obsessed with possessing Howl's heart, attempts to seize Calcifer, the fire demon who holds it. This act nearly destroys her, but Sophie's intervention saves her life. By the end, she is a pathetic yet peaceful old woman, having lost her magical abilities and her malice, finding a strange kind of peace in her powerless state.

Regarding notable abilities, the Witch of the Waste is depicted as one of the most powerful magic users in the kingdom. Her most significant power is the ability to cast powerful curses, most notably the one that ages Sophie into a ninety-year-old woman. She can also transform other beings, as she is responsible for turning a prince into the scarecrow character Turnip Head. Her magical prowess was great enough to allow her to directly challenge the kingdom's wizardry, leading to her banishment. Even after losing her powers, her knowledge of magic remains, as shown when she still senses that Calcifer holds Howl's heart. Her abilities, however, are ultimately a reflection of her character: powerful, destructive, and driven by selfish desire.