The Haruhi Suzumiya series is a set of light novels written by Nagaru Tanigawa. Originally published in Japanese, they are currently being translated into English for Western release. The series has spawned a manga and anime adaptation, as well as an anime feature film entitled The Disappearance of Haruhi Suzumiya, based on the novel of the same name.
Haruhi Suzumiya is also the name of the series' focal character (not a protagonist in the typical sense, however), a hyperactive, overenthusiastic high schooler who must be kept entertained at all times lest the universe start falling apart. Or something like that, nobody's really sure how it works.
IMPORTANT NOTE: Agents operating in the Haruhi Suzumiya-verse should be exceedingly careful when dealing with Haruhi Suzumiya herself. If she or the Sue is threatened in her presence, she may produce 'closed space'; if this process is allowed to continue unchecked, it will lead to the effective destruction of the universe. Tell-tale signs include a sudden loss of colour in the immediate area and the appearance of Celestials, giant, blue, translucent creatures with glowing red eyes who smash nearby buildings (decidedly not the mini version). Should this occur, agents must endeavour to complete the mission as quickly as possible at all costs, lest the closed space grow too big to collapse.