Nellie Oleson is the daughter of Nels and Harriet Oleson, the owners of the local mercantile. She has one sibling, Willie and both often tease Laura and Mary Ingalls. Nellie has a personality like her mother, both leading most of the town gossip and cruelty. (Retrieved from "http://littlehouse.wikia.com/wiki/Nellie_Oleson".)
Nellie also has a MySpace page. You can find that by clicking HERE. Note that her heroes are Attila the Hun, her mom, Sally Struthers, Joan Rivers, Alexis Carrington, and Omarosa.
And, from TV Land:
Nellie Oleson is Walnut Grove's richest and best-dressed young girl in town. She's also the most spoiled, unpleasant and disrespectful girl as well. As the daughter of wealthy Oleson family, Nellie is used to having her way. Her mother, Harriet, insists on it. And when things go her way, everyone can be certain that Nellie will brag about it. Her condescending behavior makes her the least favorite with the boys. But Nellie doesn't worry about not being popular. She believes she's the envy of all the schoolgirls, all but Laura. Nellie thinks that Laura's impoverished upbringing is something to pity. It doesn't matter to her that Laura is smart, well-liked and comes from a respected family. According to Nellie and her mother, the Ingalls are beneath the Olesons. But Nellie is no match for Laura. She insists that she and her family are worthy of respect while Nellie contends they're not. The robust personalities are both young girls are sure to lead to a showdown.