Shadow Gang

The shadow gang consists of at least three confirmed characters, though more may exist.

Members and Goals
Characters in the Shadow Gang include the shadow overlord, Gary, and one other shadow creature, who is unnamed in the comics but has been canonically confirmed to be Arnold the Third (nicknamed Arnie by fans). Most of those shadow creatures have been condemned to eternal suffering.

The structure is authoritarian, with smaller, less powerful shadow creatures terrified of the overlord. This dictator does not seem to have any qualms about sentencing Gary and Arnold the Third to eternal suffering at a moment's notice.

In Elemental #2, Gary wrongly kidnapped Luna, thinking she was a "source" (also called a creator, thought to be Aurora). This implies that they need one of these to accomplish their goals. However, not much is known about the Shadow Gang so far.

Elemental #2
So far, the shadow creatures have only appeared in Episode 2. They kidnapped Luna, then realized it was Aurora they were looking for.