The Literature Club is a club formed by seniors of North High. Yuki Nagato was the only one left when they all graduated (by year 0). This club was later taken over by the SOS Brigade when Haruhi insisted on stealing its clubroom, arguing it wasn't a "real" club due to only having one member.
Haruhi frequently used the Literature Club's budget for SOS Brigade activities, such as buying baseball uniforms and filming a movie. (Yuki allowed her to do so.)
In Editor in Chief★Straight Ahead!, the Student Council President threatened to disband the club, since it had not performed any activities that year. Nagato and the other members of the SOS Brigade had to write a magazine in order to preserve the club, and friends, allies and even rivals of the SOS Brigade were dragooned into writing articles. The scheme was successful.
The next year, the Student Council funded the club again, and Nagato tried to invite new members to the club, but her speech was so boring the visitors all fell asleep.