Charlie Bucket
Charlie Bucket is the title character in the Roald Dahl children's book Charlie and the Chocolate Factory and its sequel, Charlie and the Great Glass Elevator. He is shown in all versions of the story to have strong moral character in contrast to the rest of the children who visit Willy Wonka's factory.

Charlie is perhaps portrayed most uniformly between all three versions. He is always shown as being a stereotypically “selfless” child in a poor family. The reason he found the ticket was out of pure luck, having found money lying in the street, giving him a chance to prove himself. The reason he wins is the same throughout the three versions as well, having to do with his moral honesty. However, there were some differences in the three portrayals:

In the Book
In the original novel, Charlie is particularly quiet throughout the novel, only usually speaking to his Grandpa Joe or to Mr. Wonka, and is very concerned about the other children, both before and after they are removed from the factory. He is wise in a small way, albeit excitable and good-humored

1971 Film
In the 1971 film adaptation, Charlie and Grandpa Joe steal some Fizzy Lifting drink, and are nearly cut up by a ceiling fan as the gases in the drink send them rising. As a final test of Charlie's character, Willy Wonka reprimands Charlie for doing this, and refuses to give Charlie his prize. An infuriated Grandpa Joe vows to get revenge on Wonka by giving the Gobstopper to Arthur Slugworth. However, Charlie will not let his honesty and morality fall to the wayside, so he gives Wonka back the Everlasting Gobstopper that was meant to go to Slugworth. Having passed Wonka's test, Charlie is rewarded with ownership of the factory. Charlie in the 1971 movie also has a black-and-white TV set. This Charlie is more similar to the book version in appearance. Charlie appears to live in the same town as the Wonka factory in this version of the film.

2005 Version
In the 2005 film adaptation, Charlie continuously asks Wonka questions about his youth, often sending him into flashbacks. Charlie loves his family very much, and refuses to give them up in exchange for Wonka's factory. In the end, Charlie helps Wonka reconcile with his father, and moves his family into the factory (to be exact, into the chocolate room). Charlie's family in this particular version of events seem to be English but residing in America, though the exact location is more ambiguous than the previous film. Also, Charlie in both the 2005 and the 1971 version has a television set.
Additionally, Charlie idolizes Wonka more than in the previous film. He has a drawing of the factory, saved the wrappers of his birthday candy, and also made a scale model of the factory out of sub-quality toothpaste caps his father found at work. Although, towards the end of the film after Charlie turns down Wonka's first offer of the factory, he loses respect for Wonka because the latter doesn't hold family in such high regard. Charlie's opinion of him changes for the better, when Wonka realizes (with Charlie's help) that family is an important part of having a successful chocolate factory.
Charlie is mocked by both Augustus and Violet, but he just shrugs off their comments. Even though Veruca is spoiled rotten and Mike likes violence, they both seem to tolerate Charlie, or at least know of his plight.

Information from: Wikipedia