Age of Apocalypse
Age of Ultron
House of M
Future Imperfect
Days of Future
Are a couple examples, these worlds are what it would look like of Apocalypse, Ultron, Magneto, Maestro, or the Sentinels have succeed in taking over the world.
I know there exists an alternate future in which Kang rules supreme but I don't know it's name.
Basically I'm curious about what other such realities exists. I curious about these world because it's nice to keep in mind what horrible worlds our heroes have saved us from.