Perhaps another way to go would be to play up the psionic/gruesome horror aspect of the mindflayer, not the octopus head. Imagine a group of Zhodani special ops, whose ship crashed years ago on a sparsely populated world outside the Consulate. They were mostly telepaths, and perhaps not the most stable bunch to begin with. Over the years the strain of hiding, guilt over the assasinations they performed in their missions, combined with being away from the corrective, moderating influence of Zhodani society, has driven them all quite mad.
They have come to believe that consuming the brains of sentients will augment their own psionic powers, adding whatever small latent psionic potential their victims might have had to their own. To grow in strength, they must consume many, many brains from the deadheads who exist to serve and sustain them. Now they live a furtive, secret existance hidden in caverns, one part mindflayer, one part Hannibal Lector, one part Seany Bean.
