Here's a thought (for an event that doesn't suck);

World War III... well, World War M (Marvel)...

Some Russian breakaway country, with a secret russian super science base and a good amount of natural resources, elects a successful businessman with lots of money, who tracks down and purchases the materials necessary for a super-human army... he gets the Archangel wings from Purifiers, Ironman-esque suits from the black market, spider-virus from Spider Island, goblin-foruma-ed marines, doctor octopus-inspired seals, Intelligencia recipe for hulk soldiers, ONE Sentinel designs... and then makes an army to blitzkrieg Russia with super humans. Naturally, Russia doesn't have many super people... there's their "Big Red" or something squad, and we might imagine they have a secret cache of mutants somewhere... but faced with such devastation, they'll likely call in the Avengers to help... but they can't take on such an army. Maybe Russia even reaches out to Utopia, China's new super team, etc.

This gets the US to reinstate the initiative, train new super heroes... including mutants?...

Latveria and Dracula's kingdoms are initially neutral, but eventually have to pick a side? Hand ninja as well, etc. Fortunately the baddies want to capture/mass produce super powered persons, so there'd be relatively few casualties of war on the super hero front... yet, if the US slow-goes it, these guys could conquer half of europe in a matter of days.

I figure this event produces a half dozen "generals" of the various armies who are decent reusable villains - a "Spider General", a "Iron Lord", a "Blue Hulk" (haha), so forth and so on - the rest of the army eventually gets killed/beaten back.

This would eventually lead to WWM2, but in between we get this guy trying to create new super villains loyal to him - rather than having an army of Hulks, he figured he should have a large variety of troops, like the Avengers that defeated him... this "Project Villain" could create the next generation of super villains, culled from insane asylums, prisons, mercenaries, assassins, etc. Throw enough money into enough secret research facilities, and have them throw "controlling" nanites into them or something so the leader can gather them all together, and you should be good to go.