The Dominators were an alien race originally introduced in a Legion of Super-Heroes story in 1967 (more on that in another post). But our immediate interest in them is as the central figures in the fabulous 1988 company-wide crossover, "Invasion!"
Invasion, in my opinion was as good as most other company-wide crossover have usually been bad. There are several reasons for this:
1. The threat (alien invasion of earth) flowed logically from other stuff already happening in comics and didn't feel like an arbitrary plot device (q.v. "Millenium")
2. The aliens had a comprehensible motive, plan, and defeat.
3. "Invasion" the miniseries that tied everything together, was only three issues long.
4. "Invasion" explained important things in the DCU and how everything fits together.
5. "Invasion", despite having more lasting impact than most other crossovers combined, didn't take itself overly seriously, and had a fun "Mars Attacks!" feel to it.
Why on (or off) earth Invasion hasn't been collected in trade I cannot imagine. I'd buy it for myself and all my friends and relatives.
The essence of the story is that the Dominators consider Earth a threat, because it seems to spit out new superbeings on a weekly basis, so they form an alliance of aliens to attack and subjugate Earth. They do a pretty good job of it, too, all things considered.
Invasion did at least several important things:
- Introduced the concept of the "metagene" as an explanation for superbeings.
- Explained the relationship of Earth to all the United Planets in the 30th Century and why people from different planets all have wacky powers but look just like humans.
- Created a basis for Earth's interaction (or lack thereof) with other planets here in the 20th Century.
- Kick-started Max Lord's mindcontrol powers, leading in (eventually) to his role in Countdown to Infinite Crisis.
- Introduced Mon-El and the Daxamites in a Post-Crisis world.
- Started L.E.G.I.O.N.
As a result of Invasion, an appearance by the Dominators is literary shorthand for "alien concern over Earthers developing superpowers". And given that Mark Waid is writing Legion at the same time as participating in 52, I'm sure it's not a throwaway but a real connection...
but exactly what I can't yet imagine.