Every great hero needs a great backstory, something that shows you that they are cut from a certain cloth, a place where they learn to hold onto hope whenever it may be lacking. Cinderella had it with her stepmother and ugly sisters, and Harry Potter had it with the Dursley's.
For all of the years Harry spent fighting Voldemort and ensuring that the wizarding world didn't fall to him and his death eaters, he also had to contend with the Dursley family. His Aunt Petunia and Uncle Vernon were at best dismissive of Harry, and at their worst awful human beings.
They had little interest in taking care of Harry and their actions in the films are quite placid when compared to their description in J.K. Rowling's books.
From the grey clothes they used to make Harry wear to keeping him in the cupboard under the stairs with locks on the door, it's fair to say that they were downright negligent.
Where Petunia and Vernon were vile toward Harry, Dudley was clearly more of a spoiled brat. He wasn't mean to Harry by nature, more because it is the way his parents were toward Harry, and eventually Dudley made efforts to reconcile with his cousin.
What do you remember from the Dursley family? Find out here.