The Maiden is a fictional character in the wizarding world invented by Beedle the Bard. The character appears in both the real-world and in-universe versions of the story, The Warlock's Hairy Heart in the The Tales of Beedle the Bard.[1]
Story[]

The warlock with the maiden
The maiden is visiting her kinsfolk while the very wealthy Warlock is searching for a wife that he hopes will make him the envy of everyone. When he hears of the maiden, he is impressed by her beauty, equal wealth and is sure her magical lineage will ensure they produce gifted wizarding children.[1]
The Warlock considers her a prize but doesn't feel anything for her. Even so, he starts to pay her court to the surprise of everyone who had thought him to be cold, unfeeling and unlikely to ever marry. The maiden is both fascinated and repelled by the attention but sensed his true cold nature behind his fake efforts to appear warm. However, her family consider him a great match for her and accept the warlock's invitation of a feast for her.[1]

The Warlock's feast
During the feast, the maiden sits on a throne next to the warlock. He tries to charm her with the words of poets that he stole. The maiden is confused and tells the warlock she would be thrilled by his attentions if she only thought he had a heart.[1]
The warlock tells her not to worry and invites her to the dungeon to show her his greatest treasure. She discovers he had ripped out his own heart with the Dark Arts years earlier and it is now being kept in a crystal casket. The years it has been out of the body has shrunk it and turned it hairy and feral.[1]
The maiden is very upset and tells the warlock to put it back in his chest where it belongs. He is eager to please her so he tries to put it back with magic. The warlock takes out his wand, cuts open his chest and puts the heart back. The maiden is delighted and tells the warlock with a hug that he will now know true love.[1]

Her death
However, the hairy heart does not react kindly to her. Her voice, touch and scent pierces it and appeals to its savage nature. The warlock is driven to rip out her heart to replace his own with it. After several hours, the guests at the feast notice their long absence and try to find them. Upon entering the dungeon, they discover the maiden and the warlock stroking her heart and failing with magic to get his own hairy heart, which is refusing to return to its casket, out of his chest. He cuts his heart out with a knife and dies on her body after briefly holding both hearts.[1]