The Terra Papers by Robert Morning Sky spoke of the "Mind Eaters"...
(Or maybe it was Alien Interview by Matilda McElroy O' Donnell)

one of those anyway talked of how the present universe was built out of the "Old (but evil) Empire" where the mind eaters where the most pernicious weapon devised...

When you think about it, the mind is the fundamentally most important aspect to all life. Lose your mind and you have lost the bridge to infinite possibility and are thus trapped in relentless limitation.

.
. . Mind control is the greatest of all weapons devised by any created or creator being!