The Literary 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 occupied its clubroom in the cultural department clubhouse, arguing it wasn't a "real" club due to only having one member.
Haruhi frequently used the Literary 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 Chiefâ 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. Meanwhile, Haruhi advertised the SOS Brigade, but disguised the advertising as Literary Club material, apparently fooling the suspicious Student Council President.
In the Disappearance of Nagato Yuki-Chan universe, Nagato recruits other members to the Literary Club, starting with Ryoko Asakura and Kyon. However, none of the members have any particular interest in literature, so they rarely take part in any literary activities, as mentioned in "The Disappearance of Nagato Yuki-chan III".