Petunia Dursley performer Fiona Shaw
Petunia Dursley
Petunia Dursley  is Harry's maternal aunt, Lily Potter's older sister, Vernon's wife, Dudley's mother, and Marge's sister-in-law. She is described as a bony woman with blonde hair (though dark-haired in the films) that she passed down to her son, a "rather horsey" face and a very long neck, and spends most of her time spying on her neighbours. Her eyes are large and pale, quite unlike Lily's. Her entire family, except Lily, is made up of Muggles. According to Petunia, her parents were proud of having a witch in the family, but Petunia saw her sister as a freak. In fact, Petunia was envious and resentful of Lily's magical abilities and went so far as to write to Dumbledore, pleading to be allowed to enter Hogwarts. Dumbledore gently denied her enrolment. Afterwards, Petunia grew bitter towards the school and, by extension, towards the wizarding world in general.
Petunia has more knowledge of the wizarding world than she is initially willing to admit. After the Dementors attack Harry and Dudley, Petunia states that she knows Dementors guard the wizard prison, Azkaban. When Harry and the rest of her family look at her strangely, she explains that she heard "that awful boy" telling Lily about them years ago. Harry assumes that the "awful boy" was his father, James, but in Harry Potter and the Deathly Hallows, he learns via flashback memories that it was actually Severus Snape, who knew both Lily and Petunia when they were children. On one occasion, Petunia almost throws Harry out of their house, but when she receives a Howler from Albus Dumbledore, she decides not to send the boy away due to the agreement she had made with Dumbledore. It is later revealed that she wished to be a witch as a child.
Before the Dursleys leave Privet Drive to go into hiding, Petunia almost wishes Harry good luck, suggesting that she does feel a tiny sense of familial attachment to her nephew; however her self-imposed dislike of magic prevents her from doing so, and she leaves without a word. In the film version of Harry Potter and the Deathly Hallows – Part 1, she leaves Harry without showing any sentiment; however, in a deleted scene on the Blu-ray/DVD release, Petunia shows acknowledgment of the wizarding world, and ultimately deep sadness and remorse for the loss of her younger sister Lily, reminding Harry that she lost a sister as well. 
In Harry Potter and the Cursed Child, Petunia Dursley is mentioned as having died a few years after Harry's second son Albus Severus started studying at Hogwarts.
Actress Fiona Shaw portrays Petunia in the films, with Ariella Paradise playing her as a child.