Nightmare Vex is a Nightmare Irken Scientist. He is Invader Vex's Nightmare Dimension counterpart. Nightmare Vex used to be a commander in Nightmare Tak's army, but has since then left for an army led by Nightmare Clod, and is now second in command of the entire army. He is allied with Knox, an Irken criminal, and plans to gain control of all the Nightmare Dimension with Nightmare Clod, overthrowing Nightmare Tak.
Nightmare Vex has most of the same personality traits as Vex, but is much more cynical, demanding, and cruel. He is moderately loyal to the Empire, but often acts much on his own judgement and reasons. Nightmare Vex is cold and calculating. He does not consider other's feelings when speaking, but instead speaks purely based on facts. Nightmare Vex absolutely despises Nightmare Tak for the simple reason that she always seems to have the childish need to break things. Vex finds this terribly counterproductive, but is sworn to obey her anyway.
Nightmare Vex is proportioned exactly the same as Vex, but has gray skin, a blue PAK with silver spots, and a long black cloak. The ends of his PAK legs have spikes and can split into claws, similar to Vex's. Nightmare Vex also wears a bandolier with extra ammunition and explosives magnetically mounted to it. Vex has a similar bandolier, but rarely wears it.
The bottom of Nightmare Vex's coat dissipates much like Nightmare Professor Membrane's and Poop Dawg, the gangster specter of defeat.
Nightmare Vex's arms are mutated so much that they are not helpful for anything he does, seeing as they are more like whips and less like arms. He has six legs that are very similar to PAK legs. Some say that Nightmare Vex tried to link with his alternate dimensional counterparts, but an accident occured when the bond went too deep. When a disabiling injury happened to a counterpart, his legs also were disabled, and needed replacement. His replacement legs are as sharp as daggers and as silent as the wind, making him very agile.
Invader Vex- He dislikes Vex's slightly more forgiving nature, but does not despise him as so many Nightmare Irkens despise their counterparts. They both speculate that if one of them were to die at a different time than the other, something bad would probably happen.
Nightmare Tak- He used to be somewhat loyal to Nightmare Tak, but while he respected her as a superior, he found and still finds her destructive nature often counterproductive. One time when Nightmare Vex was working on a new weapon without her consent, Nightmare Tak ordered for the whole building to be destroyed. Vex has since then left Nightmare Tak's army in favor of Nightmare Clod's new one.
Nightmare Vax- Nightmare Vex originally was friends and allies with Nightmare Vax, but his obsession with killing Vax and taking over his dimension has made Nightmare Vex turn away from him. They aren't friends nor allies, but are not enemies either.
Nightmare Ark- Nightmare Vex loathes her complete and utter need for destruction, seeing that she destroys nearly everything in her path.
Nightmare Jib- Nightmare Vex knows that Nightmare Jib isn't a real Nightmare Irken, because he was present in the building where, when trying to save the real one, he died. Nightmare Vex nevertheless is friends, to some extent, with him.
Nightmare Clod- Nightmare Vex is second in command of Nightmare Clod's newly formed army, and has since then remotely destroyed all his inventions being used by the first Nightmare Irken army. Nightmare Vex respects Nightmare Clod for breaking away from Nightmare Tak, something he himself wouldn't do on his own.
"I'm in a room full of idiots... IDIOTS!!!"
"Ya know, you may be more scared of Nightmare Tak than of me, but would you rather be quickly vaporized, or slowly and mercilessly be strewn across a dissection table?"
"Your foolish religion means nothing. Science is an undeniable truth"
"I'm gonna blow you to bits! A bit over here, a bit over there, and a bit waaayyy back there."