In the Sluggy multiverse, there is an infinite number of alternate realities, referred to as dimensions. These presumably include every possible configuration of affairs, and as such range from slightly different alternate versions of each other to completely bizarre alternate versions of each other and totally unrelated worlds. "Dimensional fluxes" and gateways of different sorts are rare but exist, allowing travel between different realities. The Dimensional Flux Agitator allows creation of these on purpose, though without coordinates it just pokes a hole in reality in random.
The dimension the protagonists usually reside in has been referred to as "The Dimension of Sluggy", "The Dimension of Nifty" and "Sluggy Prime", though no name was ever used for it by Pete. Other known canonical dimensions include the following. (Names that are in quotes do not appear in the comic, even implicitly or unofficially.)
- The (so-called) Dimension of Lame
- "The Weird Portuguese-Speaking Dimension" (well, what else are you going to call it?)
- "The Ghoul Dimension"
- The "Dimension of Rain"
- "The Bizarre Tentacle Dimension"
- A dimension where Torg was a fish (wearing a flannel).
- A dimension where Torg was a big, hairy werewolf-thing (Torgggr).
- A dimension or two separate ones where Torg was a jerk and Kiki was downright mean (see Alt-alt-Torg and Alt-alt-Kiki).
- "The Dimension of Science Fiction"
- The Punyverse
- Hell
- The Never (presumably a dimension)
- The Dimension of Pain
- The Dimension of Sham-Pain
- The Dimension of Grief
- The Dimension of Crabby Chain-Smoking Biddies
- The Dimension of Topless Rumba Cubano Dancing Cheerleaders
- The Dimension of Sentient Cream Pies with Great Comic Timing
- "The Butterflied Dimension"
- A Spirit World
Dimensions named in guest strips not confirmed to be canon include
- The Dimension of Swelling and Numbness
- The Dimension of Poing Horribiki
- The Dimension of Partially Clips
It's also possible to enter another "world" in some sense while presumably staying in the same dimension, such as by being dropped out of time.