The ninety-one governors are the angels distributed across the thirty Enochian Aethyrs, three to most Aethyrs, four to a few, each with a name, a sigil traced on the Great Table (the grid of letters at the heart of the Enochian system), and a region of the earth attributed to it. They come from the scrying records of John Dee and Edward Kelley.
Each governor rules a portion of the world and is invoked as part of the working of its Aethyr, so that the ninety-one together map the whole earth onto the Enochian heavens in an elaborate correspondence of angel, place and call.