Nightmare demon Nightmare demon was the name of a near - mythical species from the planet of Droxine . They were small - sized primates with two tails , suction cup - tipped fingers and a bare head that resembled the Human skull . Nightmare demons had strong telepathic abilities that allowed them to drive other beings mad with nightmarish hallucinations . While they were believed to have been exterminated some time before the Clone Wars , some nightmare demons had survived the slaughter and fallen under Imperial control . In 3 ABY , a surviving demon named Reist attempted to murder the Rebel hero Luke Skywalker , only to be slain himself . Biology and appearance . Nightmare demons were a species of small sentient primates , thus belonging to the same order of mammals as Humans . As such , they were anthropoid in shape , characterized by a torso with four limbs and a single head attached to it . They had a fur - covered body and two tails . Their arms ended with four - fingered hands , while their feet only had three toes . Those fingers and toes were all very flexible and ended with suction cups . The nightmare demons ' cranium , unlike the rest of their body , was hairless , exposing their apparent exoskeleton . Their skull looked very similar to that of the Humans , only much smaller , and their deep - set eyes flashed with eerie bursts of light . They were small enough to fit on a Human ' s forearm without discomfort . In addition to being supple and nimble , the nightmare demons demonstrated powerful telepathic abilities . They were able to enter a being ' s mind and immobilize them with their worst fears — hence their name . However , their telepathy had its limits , as it could be blocked by lead . History . Nightmare demons evolved on the planet of Droxine , located within the Esstran sector of the Outer Rim region of the galaxy . Although not part of it , their home planet was close to the Sith Worlds , the crib of the dreaded Sith civilization . Between 3959 and 3956 BBY , the demons ' home planet was part of the territory assimilated by Darth Revan ' s Sith Empire . The nightmare demons were thought to have been completely wiped out at some point before the Clone Wars , a pan - galactic conflict that raged from 22 to 19 BBY and ended with the proclamation of the Galactic Empire . However , a few nightmare demons did survive the slaughter and went on to live during the ensuing Imperial Period . Nightmare demons in the galaxy . The nightmare demons who had survived their speciecide were eventually recovered by the Empire , who partenered them with high - level assassins chosen by Palpatine , the Galactic Emperor himself . Those who were tasked with exploiting the demons ' skills would make them wear a lead - lined hood , just to shield themselves from a potentially treacherous attempt . Because of the terrible mental powers they wielded , members of other species often displayed hate and fear when meeting a nightmare demon , and the creature , in return , could feel those ill emotions . One of the surviving demons , a male named Reist , was paired up with Altin Wuho , a Human replica droid who was , by his very nature , immune to Reist ' s telepathic powers . Around 3 ABY , shortly after the Battle of Hoth , Wuho unleashed his nightmare demon partner on Luke Skywalker , a hero and ace pilot of the Rebel Alliance . After experiencing a series of hope - draining visions , Skywalker was able to use the Force to overcome the powers of Reist . Reaching his lightsaber , the pilot struck the demon in the chest , mortally wounding him . Behind the scenes . The nightmare demons were created by Steve Moore and first appeared in his comic " " , published in 1981 .