In order of importance

Nick Carraway:
Nick Carraway is the narrator of this story. As you can see on the first page Nick holds himself in higher esteem than the other characters in the novel. Even though Nick is the narrator he should not be completely trusted. On the first page he boasts about how he doesn't judge people yet throughout the story he's judging people. The only person who he envies though is Gatsby. On [page 2] Nick says about Gatsby, "He has an extraordinary gift for hope, a romantic readiness such as I have never found in any other person and which it is not likely I shall ever find again." Also, for someone with such high moral values he doesn't handle commitment very well. That's probably a main reason why he left the Mid West and it's part of why he ended up going back. Nick left the Mid West to be a stock broker in New York but didn't get rich, yet everywhere he looks these amoral people are rolling in the wealth. That's a clue to one of the main themes....

Jay Gatsby:
Gatsby is the rich, majestic, protagonist of the novel. While it isn't clear how he made all his money, he inherited most of it, and it is obvious that the other majority is through illegal dealings in organized crime with the help of Meyer Wolfsheim. It is also clear that the driving motivation for getting all this cash is so that it will appeal to Daisy. Daisy was the rich girl that he fell in love with before he joined the service. Unfortunately he just didn't have enough money to keep her while he was overseas. When Gatsby got back she was married to someone else but that didn't disuade him in the least. Gatsby's whole efforts in this book are focused on trying to bring him and Daisy back to the point of time before he joined the army except this time he has enough money for her. Gatsby says it himself on [page 111], "Can't repeat the past? Why of course you can!."

Daisy Buchanan:
Daisy is the woman Gatsby is trying to win back and coincidentally she is also Nick's second cousin. Daisy doesn't have a strong will and she cracks under pressure as shown late in the book in the hotel scene. She is the original material girl and focuses on the outward instead of the inward. Tom bought her love with a three hundred thousand dollar necklace, and now Gatsby is doing it with a huge mansion.

Tom Buchanan:
Tom is the antagonist in this novel. While Gatsby was fighting in World War I Tom was using his wealth to sweep Daisy off her feet. Tom is a yuppy and clearly in the way of Gatsby's love for Daisy. He is having an affair, which he makes no attempt to keep secret, with Myrtle Wilson while stringing along Myrtle's husband on a business deal. He treats Myrtle even worse than Daisy because in his eyes Daisy is worth a three hundred thousand dollar pearl necklace while Myrtle is worth a dog leash. With that fact in mind it is reasonable to assume Fitzgerald is telling us that Tom considers Myrtle to be his pet dog. Tom is just the bad guy in this story and you could not possibly like him.

Jordan Baker:
Jordan is the woman in this story who connects Gatsby to Nick and consequently Gatsby to Daisy. Jordan is also a friend of Daisy's while she has something going with Nick during the story. She has short hair and plays golf which back in the twenty's was uncommon for women. Therefore you can assume she acts like a guy. She is very into the Roaring Twenty's party scene and is carelessly going through life. The carelessness comes out when she's driving with Nick on [page 63]:

Nick: You're a rotten driver, either you ought to be more careful or you oughtn't to drive at all.
Jordan: I am careful.
Nick: No you're not.
Jordan: Well, other people are.
Nick: What's that got to do with it
Jordan: They'll keep out of my way, It takes two to make an accident
Nick: Suppose you met somebody just as