If any one medium brings about the fear of the impending robot apocalypse more than the Matrix, Terminator or Blade Runner films, it would have to be Star Trek: the Next Generation. The highest-rated Trek show introduced us to the Borg, a hive-minded race of cyborgs, bent on assimilating organic species to add to their collective diversity.
If that trifecta of robot horror tropes isn't enough to rattle you, they've got one more thing up their sleeve. They can adapt to any sort of attack, so if you don't take them out in one massive sneak attack, then you're in for an Undertaker-style resurrection and the realization that yes, your resistance is futile.
This adaptive aspect of the Borg may soon come into existence, thanks to robot sympathizers over at the Fraunhofer Institute (the guys responsible for the MP3 compression algorithm). They've developed robots which can adapt to any situation. The Fraunhofer researchers call them Genetic Robots, since the Borg is still trademarked.
A genetic algorithm calculates the best assemblage of robo-parts that can traverse a particular hazard, like a maze or uneven surface. A 3-D printer then starts churning out the unstoppable little machines, now configured to easily tackle the humans' pathetic attempt to stop their onslaught.
Thankfully, the system can only craft robots made out of cylinders and ball-and-socket joints, so we can still take them out while it's early. Because if we don't stop them now, it's only a matter of time before they start adapting to more complex forms, and start requiring organic components to further improve their design. And by organic components, I mean Patrick Stewart's Captain Jean-Luc Picard.