These are the five main characters ;)
Here we have Haruhi Suzumiya! She is an energetic, in-control, hyper girl. Haruhi loves the mysteries of the world such as aliens, time travelers, and espers. One day she wishes for these 3 mysteries beings to come to her, and they do! She creates a club called the S.O.S. Brigade with her 4 friends of which 3 of them are one of these mysteries beings. Haruhi is a very special girl, but she doesn't know it. She tends to go out of hand in trying to do things like dressing up in a bunny suit and forcing Mikuru in one too to get publicity for her club, and dressing Mikuru in a maid uniform. Through out the manga/anime she develops feelings for Kyon.
This is Kyon! Kyon is the narrator and the main protagonist of the series. He is a student, with whom Haruhi willingly interacted. Even though Haruhi is the title character, the story is told through his viewpoint. Through narration and dialogue, he provides his insight, perspective, and opinions on the series' events. He is both straight-man and a source of sardonic humour. While Kyon's intentions toward defending his Brigade fellows from Haruhi's madness are often well intentioned, he often has to struggle to overcome the crazy and often ridiculous obstacles barring his way. While he's not afraid to stand up to a Haruhi tangent, he does exhibit a form of fear over her occasional troublesome antics that could threaten expulsion or worse. Kyon is, in fact, a nickname. Kyon's real name is yet to be revealed.
This is the kawaii Mikuru~!She is a time traveler, assigned in the future to investigate the reason for the inability to travel to any point in time before three years prior to the present story. Mikuru is very shy and timid and unfortunately, the odd end out of many a Haruhi eccentricity. Whenever she speaks of her mission or of her time plane, she inserts the word 'classified' into spots that would ordinarily reveal important information. In the English version, she answers all of Kyon's probing questions with 'That's classified'. Occasionally, Mikuru's older self will appear in the same time plane, essentially threatening a time paradox should anyone other than Kyon find out, meaning these visitations are exceedingly rare and unpredictable. Mikuru was forced by Haruhi to play the role of a time traveling battle waitress from the future in a parody of many different magical girl anime, all of which contain Haruhi's favorite theme: moe...
Here we have the wonderful alien, Yuki~! *hehe* She is a Data Entity whose responsibility involves the monitoring of Haruhi and the investigation of the events three years prior to the present story. As a Data Entity, she possesses the ability to manipulate the surrounding environment as she sees fit. For the movie, Yuki, never heard to voice a complaint of any kind, was pushed into playing the evil alien witch, complete with the stereotypical witch costume and the mysterious talking cat belonging to Kyon. Yuki rarely speaks, choosing her books over idle conversation nine times out of ten. On the rare occasion she does choose to explain something, all middle ground is lost. She goes in depth and in detail, with nothing left out, often going into run-on sentences without even stopping for a breath.
Kore wa Itsuki desu! (this is Itsuki) He is an esper (one who possesses Extra-Sensory Perception), who had suddenly acquired the knowledge and powers of an esper three years prior to the present story. Along with other espers, he uses his power to combat the Haruhi-created beings of energy within Closed Spaces during times of fitful irritation at the lack of strange phenomena in her world. Just like the other members, his so-called Agency and its members are never explored in-depth. In the movie, Itsuki was pushed into playing a typical, somewhat dizzy and scatterbrained high school boy with powerful hidden abilities that could only be brought out by a catalyst of some sort. He is pretty much always happy, he has high spirits, and has a good sense of humor :)
So yep! (>.<) I HIGHLY recomend you all read or watch it~! :) But WARNING, if you watch it, DO NOT watch the fan dubs! Watch it with the english subtitles because their voice sound EXTREMELY weird in the english dubs~
Well....that's all for now! Peace~!<3
P.S. All info came from http://en.wikipedia.org/wiki/Haruhi_Suzumiya