ah ok.. and no jan... dont know if you heard but DS is no more. they split up. deft took leemu and toonces and many nmor eof the core group to start a new guild. they are on dantooine.
ok so then grand admiral is the correct one:
this was the highest rank an Imperial Navy officer could reach, originally establihed by Emperor Palpatine during Fete Week two years prior to the Battle of Yavin. At the time of the Battle of Endor, there were only twelve Grand Admirals in the Navy. They were distinguished from other Imperial officers by their stark, white uniforms, and Palpatine often referred to them as his "Circle of Twelve". The Alliance maintained records of each Grand Admiral's whereabouts, in order to ensure that they didn't get a chance to rally Imperial forces. Among the twelve known Grand Admirals at that time were Martio Batch, Nial Declann, Josef Grunger, Ishin Il-Raz, Afsheen Makati, Danetta Pitta, Pecatti Syn, Miltin Takel, Osvald Teshik, Rufaan Tigellinus, Demetrius Zaarin, and the so-called "Last Grand Admiral," Admiral Grant. The most infamous of them all, however, was the thirteenth Grand Admiral, Thrawn, who filled the void left when Zaarin was killed during his own attempt to become Emperor. By the time the Imperial Remnant agreed to a peace treaty with the New Republic, Pellaeon was believed to the only surviving Grand Admiral, a rank he had earned well after the death of Thrawn.
and after reading through a list of ranks... i hardly know what higher then that... the HIGH INQUISITOR seems to work directly under the emperor... but the emperor's hand... Like Mara Jade had an awefull lot of power aswell. but that wasnt really a rank like the inquisitor.. so ill go with the HIGH INQUISITOR. again a guess
this was the name given to the Imperial Dark Side adepts who worked directly for Emperor Palpatine, rooting out potential sources of Jedi candidates and Force activity during the height of the New Order. Known collectively as the Inquisitorious, the High Inquisitors struck fear into the hearts of beings by their mere presence. Through the efforts of the High Inquisitors, Emperor Palpatine hoped complete his Jedi Purge and eliminate any possible threat from the Jedi Knights.
dont think its correct tho