In previous parts I discussed teams and organizations and people and places but you may have noticed that everything I've talked about only deals with Earth. This installment will remedy that with a look at some of the common alien civilizations, groups, and worlds in these type of settings. I'll also cover some of the dimensions too.
The NeighborsThe Neighbors are an Alien (or modified Human!) species living right in our solar system, usually on a terrestrial planet but also found on the Jovian planets or our own moon (!). Such species are technologically advanced but usually few in number. Individuals also have superhuman powers, making the perfect material for heroes or villains. Their society and culture tend be isolationist and they are usually a civilization in decline or rebuilding from some great disaster.
Examples in comics: Martians (DC), Inhumans
The Space CopsEndowed with cosmic power by a group of Aliens with big egos, the Space Cops police a large portion of the galaxy or universe. Recruits are drawn from a myriad of species, although there's inevitably a hot-shot Human rookie that some think might become the best Space Cop ever. The founders of the Space Cops are a little distant and their actually authority to enforce space laws is pretty sketchy but most civilizations at least pretend to care.
Examples in comics: Green Lanterns, Nova Corps
The Militaristic EmpiresTwo (or more) empires that frequently war with each other, often dragging other planets into their own brutal wars. One or both empires also consider Earth to be a key strategic point in this war and will often attempt to conquer it.
Examples in comics: Kree and Skrull Empires, Rann and Thanagar
The God-WorldThis larger-than-life world is inhabited by beings that identify themselves as gods and have the power to back up their claims. Although the average "god" isn't necessarily superhuman, the people higher up on the totem are ridiculously powerful. Their technology is so advanced that it either seems or IS magic. The gods often meddle on Earth and other planets, sometimes for altruistic or selfish motives. In some cases there might be a second God-World inhabited only by evil gods.
Examples in comics: New Genesis and Apokalips, Asgard (Marvel)
The Three Cosmic BeingsThe Three Cosmic Beings are extremely powerful wild cards that follow their own agendas. One is Benevolent, and will often help Earth or other beleaguered planets; another is Malevolent and wants to kill/eat/enslave most of the galaxy; the final is Neutral, pursuing its goal single-minded and sometimes breaking the rules along the way. These three don't have to be actively opposing each other; They may not even be fully aware of each other. If the Malevolent being gets too crazy then the Neutral being will aid the Benevolent out of self-interest.
Examples in comics: Silver Surfer/Terrax/Galactus, Highfather/Darkseid/Metron
Now, let's veer off in a more mystical direction with dimensions:
The Hell DimensionWhether based on traditional fire-and-brimstone imagery or something stranger, the Hell Dimension is home to both what Humans would call demons and the souls of evil people (or people who signed contracts). Evil magic-users tend to draw their powers from this realm. The head honcho is usually a stand-in/analogue of the devil, although he/it is rarely presented as THE devil. Likewise, there are sometimes multiple Hell Dimensions.
Examples in comics: Neron's Underworld, Mephisto's Hell, Dormammu's Dark Dimension, Darkseid's Apokalips (debateable)
The Afterlife Dimension(s)There are also dimensions based on almost every religious conception of the afterlife, although the Judeo-Christian Heaven tends to only be hinted at (see the ends of Thunderstrike and Ostrander's Spectre). The afterlife dimension are really just set-ups to meet departed friends or foes, not for full adventures.
The Magic DimensionQuite simply an excuse to throw weird shit at the heroes and villains, the magic dimension(s) make a mockery of rational thought and real world physics. Magical characters get stronger and slightly more unhinged in these places.
That's all for now. Next: Alternate timelines, possible futures, and the multiverse.