My ex-wife, just because as much as I'm past her, I'm a vindictive bastard and she's the one who called off the marriage.
Every Hollywood celebrity. All of 'em. If they have day jobs and just happen to be famous, I spare them (the M5 Clause, because Jamie Hyneman and Adam Savage could always just go back to doing special effects...but then again, I just killed Hollywood. Sorry about your client base, guys. But hey! Your ratings will go up now that you're the only game in town!)
I would turn Washington, DC into a real-life version of the Capital Wasteland. Wiping that city off the map would be doing the world a favor, and the place would be improved by the presence of Super Mutants. (and before you start whining about your particular political party being a bunch of saints, please drink this nice cup of shut the fuck up first.)
And if I had the powers to do so, I'd change the fundamental laws of chemistry such that stuff like ghouls, Super Mutants, and comic-book mutations were real.