So, I've found this to be a fun trick.

Need a quick enemy?  Take some creature type that used to be scary, but is now just cliche.  Say, vampires.

Boil down the essence of what makes them scary:  Vampires are super-powerful, feed on people, and breed more of themselves.

Ditch the superficial trappings - the cliche weaknesses, the feeding on blood, sleeping in coffins, etc.  Make new trappings - for instance... make the effect due to some kind of nasty worm that ends up living in your trachea.  Make the consumption of others literal consumption of flesh, rather than simply blood sucking.

Bam.  New enemy.  All the good old scariness, but now you're forcing your players to deal with it for the first time.

This works with all kinds of nasty bads.  Werewolves?  Sure, have a creature that, under certain circumstances (usually anger-related) can transform into another evil, darker form and becomes a beast.  Maybe that's his real form and he simply loses the ability to hold the illusion under most circumstances.

Zombies?  Heck, what do you think Invasion of the Body Snatchers was?  All kinds of reasons to have a loss of identity and join a mindless horde - Cthulhoid madness would be a great start, or some kind of cult.

These things have become cliches because they work.  They don't work now because we're so familiar with them that the fundamental horror of them has been lost to us.  So get rid of the familiar, and keep only the horrifying.