It appears that Viz LLC. may have the largest graphic novel backlist of them all.  The current Viz catalog lists 1030 titles, of which approximately 320 are 2004 releases, 225 of which have already shipped, putting the number of Viz graphic novel trade paperbacks available to retailers at approximately 900.  This would give Viz more backlist titles than Tokyopop (c. 800), DC (c. 700), or Dark Horse (c.575) (see 'Tokyopop Passes DC'--figures for the Viz backlist were not available to ICv2 in time for inclusion in the 'Tokyopop Passes DC' article).

Viz and Tokyopop are the top two manga publishers in the U.S. and the extent of their considerable backlists is testimony the popularity of manga, especially in the bookstore market where manga dominates graphic novel sales.