Any non-mutant X-Men villains that give the X-Men a lot of trouble?

So any non-x-men villains like Dr. Doom, Green Goblin, Loki etc that have been great villains for the X-Men.

So having X-men team with Fantastic Four to take out Dr. Doom doesn't count.

It has to be like for example: Ultron vs X-men.

Or is it impossible to get villain crossovers without their primary heroes following them?

Well Juggernaut comes to mind. He's not a mutant.

@thorson: Loki and the Enchantress were primary villains during the "Asgardian Wars", which is not only kind of the first "X-over" in Marvel history, but is one of some people's (mine!) favorite crossovers.

The X-men have faced lots of non-X-men villains on their own, most of the big ones anyway, Dr.Doom, Loki, the Red Skull, Dracula, Baron von Strucker, Galactus, Impossible Man, The Beyonder..

But their own rogues gallery has a lot of non-mutant mainstays anyway: Juggernaut, the Sentinels, Sauron, Arcade, the Brood, Mr. Sinister, the Friends of Humanity, the U-Men, Mojo, the Reavers, Lady Deathstrike.. the list goes on.

Sentinels - mutant hunting robots

Lady Deathstrike and the Reavers - cyborg mercenarys

Sublime - A human possessing bacteria who can't possess mutants

Any mutant hating human

Pandemic - A scientist who copied Rogue's power

Unit - A android who can talk a person into doing anything he wants

Doom and Dracula popped in once or twice.

He's a known x-men villain/anti-hero. He doesn't count.

The Sh'iar can cont since they are some time adversary to the x-men.

They fought Galactus?!!!! When was this? Crap I must have missed something. -_-

The Blob (He isnt mutant, he is just fat)

Juggernaut

Purifiers

U-Men

X-Terminated

Demons and beings from Limbo

Humans

S.H.I.E.L.D and Avengers during Marvel Now Uncanny Avengers

Wait, wha???? No. Just no. Although, it would be funny considering he has been on like ten incarnations of the Brotherhood of Evil Mutants. They could reveal he was lying on his application or something.

@cattlebattle: I thought he wasnt. I saw lot of people mention that he wasnt. Maybe was because of House of M.

I think it was in Excalibur with Rachel.

1999? I think the story ran through X-Men and Uncanny' at the time. I wasn't paying a lot of attention then, but I couldn't bring myself to drop the book right when Alan Davis had come back..

Speaking of, I'm pretty sure Rachel Grey fought Galactus by herself in Excalibur..

Most x-men villains are humans or aliens.

@oldnightcrawler:mr sinister isnt a mutant???

Sinister was just an extraordinarily brilliant human biologist with grand designs; he actually got all of his powers from Apocalypse (which is why they have basically the same powers). The story's in The Further Adventures of Cyclops and Phoenix, from 1996; it's basically Sinister's origin story. It's worth a read.

X-Men/Spider-Man (actually called Spider-man/X-men on the cover) from 2009 is another really fun Sinister story.. though, like most, he's not actually in it that much..

Humanity is the ultimate villain.

most marvel characters are humans or aliens.

including the X-men.

Purifiers.

Still waiting for a leader who will resemble Magneto, but one will need the balls to write that kind of story giving overzealous villains shades of grey.

Belasco and the Elder Gods.

The Avengers/Shield

Gingrich

The Brood

Arcade