Lord High Inquisitor is the proper title for the ruler of the Rigellian Empire, but the current Lord High Inquisitor has held the title for so long (far longer than the lifespans of your average Rigellian) that no one living remembers how he became installed in the post or even what his name or origins were before he achieved it, not even his nephew Frank. As the Inquisitor was recently sucked into a small spontaneously occurring black hole, Frank has assumed control of the Empire.
First (web) appearance of the Lord High Inquisitor.