Oh, as we talk about the late game...
European civ, anyone?
They could rise after 1950 from any after-war congress and include all European civs that are Unstable/Collapsing at that moment, plus all Independent cities in Europe.
Europe would have the core of: Dutch, France, Prussia, Austria, southern Skandinavia; with England, Spain, Portugal, Italy, Poland and Greece as historical area. Colonies would be returned to original owners (maybe resurrect those civs as well). In return for such a huge core, all cities outside Europe should get some sort of severe penalty.
Unique Power: Power of Integration: All European civs that become instable after 1950, are flipping their continental cities into the EU, bringing all their units, technology and treasury with them.
Unique Unit: Bureaucrat (replaces Spy). Special promotion: When stationed in an EU city, it increases commerce by 10%, not cumulative.
Unique Building: Standardization Office (replaces courthouse): When not at war, corporations lose their unhappiness and unhealth effects.
UHV victory:
European Markets: Department Store, Supermarket, Hotel and Electrical Grid need to be present in half your cities, by 1990.
European Union: Control (80? 90? 100%?) of the core and historical parts of Europe until 2030 without ever declaring war (on Europeans, or at all)
European Council: Have open borders with your five most powerful rival civs while you are in office as UN Secretary General