What is the SOS?
The SOS Brigade (SOS団 (エス・オー・エスだん) Esuōesu dan) is a club that Haruhi started shortly after entering high school. The club name is an scronym of "Sekai wo Ooini Moriagerutame no Suzumiya Haruhi no Dan" (世界を大いに盛り上げるための涼宮ハルヒの団), which roughly translates into "Haruhi Suzumiya's Brigade to Greatly Enliven the World". To retain the acronym, the official North American adaption refers to the group as the "Spreading Excitement All Over the World with the Haruhi Suzumiya Brigade", whilst unofficial fan translations generally adopted the title "Save the World by Overloading it with Fun, Haruhi Suzumiya's Brigade".
Haruhi initially received the club idea when Kyon lectured her about how meaningful inventions throughout history were created by geniuses: that technological advancements in the world were wrought by a limited number of lucky individuals. Inspired by this speech, Haruhi decides to create a club to address the woeful lack of aliens, time travelers and espers in her life.
The goal of the SOS Brigade is to "Bring More Excitement to the World". The club's main contribution is a film intended for the High School cultural festival entitled The Adventures of Mikuru Asahina: Episode 00 starring Mikuru, Yuki, and Itsuki as the main characters. It was filmed and narrated by Kyon and directed by Haruhi. Kyon edited the movie during an all-nighter, which resulted in poorly edited work and story incoherence. The film's plot consists of a number of meta-fictional parodies of anime clichés.
In addition to the movie project, Haruhi involves the club in various activities such as participation in a baseball tournament and a summer trip to a tropical island owned by one of Itsuki's acquaintances. All such activities prevent Haruhi from boredom.
The original emblem by Haruhi was very unrefined and resembled "a
grumbling drunken tapeworm" according to Kyon. Nagato informed Kyon,
after the Cave Cricket encounter, that its data was far too large for
terrestrial standards for conversion, which was utilized by the
Cricket. The final version appears refined but the "S" are actually
backwards and more closely resemble "Z" in order to avoid another Cave
Cricket incident.
The SOS brigade's logo
Join the SOS
Members in red are already spoken for.
SOS-dan members
Haruhi Suzumiya (涼宮 ハルヒ Suzumiya Haruhi)
The title character and leader of the SOS Brigade. Her energetic
and eccentric character proves to be a driving force for the series. 
- A student, with whom Haruhi willingly interacted. Even though
Haruhi is the title character, the story is told through his viewpoint.
Through narration and dialog, he provides his insight, perspective, and
opinions on the series' events.
Yuki Nagato (長門 有希 Nagato Yuki)
- 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. Also, she has
the capability to access closed space.
Mikuru Asahina (朝比奈 みくる Asahina Mikuru)
- She is a time traveler. Like Yuki, she is assigned from the future
to investigate the reason for the inability to travel to any point in
time before three years prior to the present story.
Itsuki Koizumi (古泉 一樹 Koizumi Itsuki)
- He is an esper. He 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 beings of energy within Closed Space.
