"I won't have this namby-pamby, wishy-washy nonsense about not hitting people who deserve it. A good thrashing is what's needed in ninety-nine cases out of a hundred. Have you been beaten often?"
     -- Aunt Marge to Harry

"Bad blood will out. Now, I'm saying nothing against your family, Petunia, but your sister was a bad egg. They turn up in the best families. Then she ran off with a wastrel and here's the result right in front of us."
     -- Aunt Marge

Miss Marjorie Dursley is Vernon's sister. She lives in the country, in a house with a large garden, where she breeds bulldogs. She has twelve dogs, her favorite of which is an old and evil-tempered dog named Ripper. She takes Ripper with her when she visits. Even though she is not Harry's blood relation, he has been forced to call her "Aunt" all his life. Marge looks a lot like Uncle Vernon: "large, beefy, and purple- faced, she even ha(s) a mustache, though not as bushy as his." She allows Ripper to slurp tea from her saucer, splattering saliva and tea on Aunt Petunia's immaculately clean kitchen floor.

Aunt Marge considers Harry to be inferior in breeding, the way she says a pup would be inferior if it came from inferior stock. She abuses Harry and derides his mother and especially his father, calling them drunks and layabouts and saying that they got what they deserved. She has been told by Vernon that Harry goes to St. Brutus's Secure Center for Incurably Criminal Boys. She suggests that he should get plenty of beatings while he's there.

Dudley allows Aunt Marge to coddle him because he is well paid for it. When she kisses and hugs her "little neffy-poo" upon entering the house, Dudley steps away from the hug with a crisp twenty-pound note. She buys him expensive presents, in part as if to dare Harry to complain because he didn't get any. 

Marge eats a lot ("Excellent nosh, Petunia!") and drinks excessively. When inebriated, she is even more abusive to Harry. In 1993, on the last night of her visit, Harry lost his temper with Marge and inflated her like a balloon. Then he ran away from home. The Ministry of Magic had to step in to deflate her and modify her memory (PA3).

Miscellaneous notes:

• sent Dudley a birthday present in 1991 (SS2)
• vacationed on the Isle of Wight (July 1991), where she got ill from eating a "funny whelk" (SS3)
• doesn't often stay at Privet Drive, because she can't bear to leave her precious dogs
• previous visits:
• Dudley's fifth birthday party (1985?) - she whacked Harry around the shins with her walking stick to stop him from beating Dudley at musical statues
• A few years later, at Christmas, brought a computerized robot for Dudley and a box of dog biscuits for Harry
• 1990: Harry accidentally stepped on Ripper's tail. Ripper chased Harry out into the garden and up a tree, and Aunt Marge refused to call him off until past midnight. Dudley still laughs about this incident.
• Col. Fubster, a retired neighbor of hers, looks after Aunt Marge's bulldogs when she's away (PA2)
• Marge accuses Harry's parents of being drunks while she herself is getting sloshed on wine and sherry (PA2)
• Marge speaks in shouts and barks (PA2)