Vernon Dursley
Age: Unknown, probably in his forties.
House: N/A. He is a Muggle.
Distinguishing Characteristics: Good at shouting. Very large moustache but very little neck. Hates everything about wizards and wizardry.
Heritage: Muggle.
Family: Married to Petunia Dursley (nee Evans). One son, Dudley Dursley. Additional adopted son, Harry Potter (his nephew by marriage, and adopted against Vernon's will).
First Mention: Vernon has the honor of being the first person mentioned in the first book.
General: Vernon Dursley ("Uncle Vernon" to Harry) is a man who is both very successful (he is director of Grunnings, a drill-making firm) and enormously fat. He also has a moustache which makes it look as though he has superglued an Afghan hound to his upper lip. Vernon likes a number of things: being normal, being seen as successful, and shouting at anybody he feels superior to, which is most people. Harry Potter is one of the few people he hasn't shouted into submission, a fact which makes him very angry, especially as he didn't want the boy in his house in the first place. Vernon turns purple and blotchy when he is angry and shouts even louder than normal, which is pretty loud. Fortunately for Vernon, Harry has decided after his sixth year at Hogwarts, to come "home" only one last time. After that, he intends to be gone from the Dursleys' doorstep forever. This will undoubtedly make Vernon and his son Dudley overjoyed. With Vernon's wife Petunia, things may not be so clear; there is some mystery behind Petunia that has not yet been solved. She seems to know more about Harry's plight than he previously thought. While it is doubtful that she will have much sympathy for Harry, she may still have some role to play.
Vernon and his wife are devoted to their son Dudley, who takes very much after his father. Vernon likes to see Dudley eat as much as possible, demand as many presents and treats as possible, and beat up as many small people as possible, congratulating him on being just like his father. By contrast, his cruel streak when applied to Harry knows no bounds. He makes Harry sleep in the cupboard under the stairs instead of a bedroom, deprives him of anything but the most basic food and possessions, and shouts at him as much as possible. Crucially, he is desperate to prevent Harry having any sort of association with the wizarding world.
This hatred of Harry and of magic at first sight appears to derive from Petunia's jealously of Harry's mother, Lily. Mr and Mrs Evans (both deceased) were delighted that Lily was a witch and Petunia felt very much left out in the cold. Having said this, Vernon's incredible zeal in attempting to keep Harry away from anything whatsoever to do with magic seems to go beyond both this and his natural desire to appear completely normal to his neighbors. Maybe he really is just trying to keep his wife happy (while enjoying a bit of shouting into the bargain) or maybe it goes further than that.