Critter (クリッター, Kurittā) is the alias of a minor antagonist in the War of the Underworld sub-arc of the Alicization Arc. He is a hacker consultant working in the cyber operations department of Glowgen Defense Systems and a first-class cyber criminal.
Critter is a skinny man with blonde hair that is cropped short, pale-grey eyes, and morbidly white skin. He wears rustic, goggle-like glasses with a metallic frame atop his scrawny cheeks.
Critter was assigned to be one of the twelve members of Glowgen Defense System's assault team on the Ocean Turtle. However, the Japan Self Defense Force (JSDF) managed to lock down the console in the main control room and locked themselves behind barrier walls before the invaders managed to reach them, preventing the invaders from being able to directly access the light cube cluster. As Critter could not hack the console and blamed the assault team for taking too long to reach it, he began arguing with Vassago Casals, another member of the team, but they were interrupted by their leader, Gabriel Miller.
Critter continued operating the console, but he could not deactivate the lock, so he brought up a view of the Dark Territory on screen. The team were surprised to see goblins in the world and Critter revealed that the goblins had human souls. As Vassago imagined that all the humans were goblins, Critter corrected him and explained that Underworld was divided into the Human Empire, where Alice Zuberg and other humans lived, and the Dark Territory, but claimed that it was impossible to find Alice by peeking into the world via the console.
When Vassago suggested going into the world and look for Alice from within and revealed that he was fluent in Japanese, Critter was about to say that it was unreasonable to ask every single resident for Alice's whereabouts, but then realised that there would be higher-ranking accounts created by Rath that would make the search easier.
As all the high-ranking accounts in the Human Empire were password-locked, Gabriel suggested looking for such accounts outside the Human Empire and use them to invade the empire. Critter found two super accounts, a dark knight and Emperor Vecta, that were not password-locked. While Vassago and Gabriel each claimed an account to use, Critter continued operating the console and discovered the term ≪Final Load Test≫.
Several moments after Critter connected Gabriel and Vassago to the Soul Translators, he was contacted by Gabriel via a system console within the Dark Territory. After Gabriel reported his and Vassago's progress, Critter reminded them what to do after they found Alice and the fact that he was unable to reset accounts, thus Gabriel and Vassago would not be able to use an administrator account if they died. Critter then reported that the JSDF had not taken action yet and Gabriel finished the call by saying that he would not contact Critter until they secured Alice.