- Thin, blonde woman
- Twice the normal amount of neck
- Shrill voice
- Horse-faced and boney
- Resident of Number four, Privet Drive
- Wife of Vernon Dursley, mother of Dudley Dursley
- Sister of Lily Potter, but estranged
- Aunt of Harry Potter
At the beginning of Harry Potter And The Philosopher's Stone, Petunia is living a normal life, until her infant nephew Harry Potter turns up on her doorstep with a letter from Albus Dumbledore. She treats Harry very poorly while he lives there, almost as a servant, compared to Dudley, whom she dotes on.
In HPPS 3, mysterious letters begin to arrive for Harry, and the Dursleys eventually flee from them. They take refuge on a hut on a rock in the ocean, but at midnight on Harry's birthday a huge man calling himself Hagrid bursts in and tells Harry that he's a wizard. Petunia angrily admits that she's known all along, but that she hated her sister being a witch, and resents that her parents were so proud. After Hagrid loses his temper and gives Dudley a pig's tail, the Dursleys retreat.