The 4 predominant theories basically say "He's one of the things that exist in this universe" That's like saying "Well I think your baby is either going to be a boy or a girl"
Zurg has purple skin, red eyes, and neon lime teeth (though this appears to be part of his helmet), and always wears the same purple armor and robe. When he speaks, his tone fluctuates often.
Zurg has a "Z" emblem on the front of his cape. The emblem is a secret button which can, when pressed, activate Zurg's rocket boot allowing him to fly.
It isn't quite known what species Evil Emperor Zurg is, but he is seen holding a cup of water, trying to eat popcorn, and also shown coming back from recently using the restroom, which may rule out him being a robot. He does have feet, once stating that he owns a pair of rocket boots to which he "got on sale".
History
File:BLOSC Clip-Psych!The moment everyone was waiting for...and it turned out to be a hoax.
Just as we know next to nothing about Commander Nebula's backstory, neither do we know how Zurg became an Evil Emperor. He owns a vastly powerful, sinister empire that constantly threatens the sanctity of the galaxy and the Galactic Alliance. It is also not shown what planets he possesses, but it is apparent that he owns several; such as the mining planet in "Shiv Katall".
In one episode, "Stranger Invasion", he told Buzz Lightyear that he was his father; however, this was a ploy to distract Buzz, which led to Zurg taking the upper hand. He was quick to pass off the claim as a "Made You Look" scheme.
Evil Emperor Zurg is not your usual despicably evil supervillain. Despite being the most evil, nefarious villain of the galaxy for years on end and a constant thorn in the side of Star Command, Zurg has been known to take himself less than seriously, and actually seems to have a well-developed (if demented) sense of humor.
His evil schemes are routinely less-than-stellar in design (such as one scheme to make children afraid to eat their vegetables so that years later they would be too weak to fight when he invades...a plan which only Buzz thought clever), and he is quick to shunt the blame for failures onto others' shoulders (usually his Grubs or Brain Pods).
His main downfall whenever fighting against Buzz Lightyear, his nemesis, is the trademark error of every villain: the gloating monologue. Because of this, Zurg has never won out of the 3,247 times [1] he's tried.
He has a strange fear of being touched, mentioning something about "personal space" and "cooties" in the episodes "The Torque Armada" and "The Main Event".
He is also somewhat picky about his schemes, claiming when politicians were being kidnapped that he would never do something "so obvious."
Abilities
He has laser vision, but rarely uses it in battle, and seems to use it when losing his temper. Whether this is a species trait or an artificial enhancement is left to the imagination of the viewer.
Zurg's signature weapon is an Ion-blaster with three pipes. Zurg uses this often, and seems skilled with it, stating at one point that the secret is to squeeze, not pull the trigger, showing he knows well how to use this weapon.
"Hold your fire. Don't damage the HYPER DEATH RAY!"
Trivia
File:Tumblr inline nmo48o37gZ1sawqm3 1280.pngZurg's species is an issue of much debate in the fandom. To this day there is no concrete answer, but there is theoretically enough evidence to rule out Zurg being a robot due to his eating and sleeping habits.
While it may not be obvious, Zurg is afraid of the dark.[2]
When enslaving the people of Roswell, Zurg states that he is an "Equal opportunity enslaver" a parody of "equal opportunity employer."
