Styx

Styx is a Decepticon penal colony in the Generation 1 continuity family.

A small ice and snow-covered moon orbiting a vast gas giant is home to the Decepticon penal colony called Styx. Of all such installations it is the harshest and most brutal. Prisoners sent to Styx have a short life-expectancy and may be better off for that. The penal colony is said to be impregnable.

Gutcruncher is stationed there.

Fiction

IDW comic continuity

Hot Rod impregnates the impregnable prison (get your mind out of the gutter) with a virus that lets him sneek in and free his former comrade, Dealer.

Although Dealer seemed appreciative, he failed to give Hot Rod a "Domo arigato".

Trivia

In Greek mythology, Styx was a river which the dead journeyed down on the way to Hades.

From Teletraan I: The Transformers Wiki, a Wikia wiki.