This is a list of the fictional characters featured in the Haruhi Suzumiya light novels, with also information pertaining to the anime adaptation, The Melancholy of Haruhi Suzumiya. These characters also appear in other adaptations including the manga, drama CDs, and video game. The title character is Haruhi Suzumiya, an energetic high school girl who forms a club called the SOS Brigade. Haruhi has an extraordinary power to change the world any way she likes, but is simultaneously unaware that she possess such a power. Despite the series being named after Haruhi, the main protagonist in the story is her friend who is known by his nickname Kyon, who also narrates the story. Kyon is the first member recruited into the SOS Brigade, and is a practical person who will stop Haruhi if she goes too far with Brigade activities. The second recruit is a quiet girl named Yuki Nagato who likes to usually keep to herself and read books. Yuki is in fact an artificial life form who has been sent to investigate Haruhi for the time being. The third recruit is a timid girl in the second year of high school named Mikuru Asahina. She is actually a time traveler from the future sent to observe Haruhi. The last member of the SOS Brigade is Itsuki Koizumi, a cheerful young man Kyon's age who is also an esper sent by his organization to observe Haruhi.
The Haruhi Suzumiya series contains a multitude of other secondary, and minor characters which are introduced throughout the course of the series. Many of these are featured as schoolmates at Haruhi's school. One important secondary character is named Ryōko Asakura who at the beginning of the story is in the same class as Haruhi, and often tries to talk with Haruhi, but is unable to due to Haruhi ignoring her. Two other classmates in Haruhi's class are Taniguchi and Kunikida, two of Kyon's friends who are usually seen together. Other principal schoolmates include Tsuruya, an energetic friend of Mikuru; Emiri Kimidori who is another artificial life form along with Ryōko; and the chairmans of the student council and Computer Research Society. Another recurring character is Kyon's Sister, whose real name like her brother is unknown.