Dark Empire is a series of comic books. Dark Empire, Dark Empire II, and Empire's End (which you can get as a hardback collection called Star Wars: Dark Empire Trilogy). There is also an RP sourcebook, called the Dark Empire Sourcebook, a handbook, and audio drama adaptations (a full, casted radio drama, with Billy Dee Williams returning as Lando Calrissian, not just an audiobook) of Dark Empire, Dark Empire II and Empire's End.