Of all the things people could go terrorist for—oppressive governments, etc.—there's a group that chose anti-nanotechnology. I wish I was kidding. They call themselves the "Individuals Tending to Savagery" and have attacked two professors in Mexico with bombs.
The group has taken credit for two bomb attacks on Mexican robotics researchers who also focus on nanotechnology. They sent the homemade bomb through the mail and addressed it to the specific professor (with threats of prosecution if someone else was to open it). The 'Individuals Tending to Savagery' aka the Idiots (my shorthand for them) believe that "nanoparticles could reproduce uncontrollably and form a 'gray goo' that would snuff out life on Earth." They believe nanotechnology has dangers to 'native species' and ties it to the natural disasters that have been happening recently.
Basically, these dudes are either so terribly afraid of change (good or bad) that they're willing to kill people who want to advance technology and make life better or they're just a bunch of idiots who heard some batshit crazy fictional theory about nanotechnology and how it'll ruin the world. Or maybe both. Either way, I think they're too stupid to even be terrorists. [Washington Post, ieee spectrum]