Fedoranuker (also known as Fedonuker or the UnMortal) is a character first seen in "The UnMortal" Forum Thread.
Secret Origins of FedoraNuker
There are all kinds of events that weaken the dimensional fabric of the universe and nature. ABS use is the most common cause; hyperspace travel stresses it as well. The supernatural nature of Immortals and the Undead add stresses of their own, and being both Immortal and Undead all in one minifig is just ridiculous. I mean what does that even mean? He can't UN-die? You can see why the BrikVerse gets confused.
So wherever Warhead goes, and especially when he goes there by ABS hyperspace travel, it causes severe dimensional turbulence. When he crosses through areas of Negaverse activity, a large amount of that turbulence bleeds through in the Nega direction - some of it radiating so far that it goes all the way past the Negaverse and into the Nega-Negaverse, where you find the twisted opposite reflections of the already twisted opposite reflections of things. In the Nega-Negaverse, Spock has two beards.
In between the regular universe and the Nega-Negaverse, the Negaverse (and, to a lesser oblivious degree, PeaceAss) acted as a focusing lens for Warhead's frequent outbursts, making bizarre distorted projections of his psychoses on the Nega-Negaplasm. Growing out of Warhead's irrational hatreds, one of these projections became self-aware, and began focusing on stoking the fires of Warhead's rage even further whenever the dimensional barriers thinned. The stronger the projection became, the more it was able to affect Warhead's dreams, until it was able to trigger a rage so fierce that it received a psychic power surge that allowed it to take physical form.
Now running around loose in the regular universe, Fedoranuker still feeds on the energy of Warhead getting pissed off at things. Having no physical basis for reality of his own, Fedonuker can assume any form and create any number of offshoot underlings. However, because of the way he was created, his imagination is limited to stuff Warhead hates, and so mostly he creates different variations of Pandoranuker rather than doing anything useful like disguising himself as one of Warhead's allies and betraying him. Killing Fedoranuker has no real effect, since he reforms instantly, but at the same time he's not interested in killing anyone else either, since he needs their butthurt to feed on.