Uh... You can... It's called "murder" though.
As for whom I would execute given the chance to get away with it? Oh dear... About half the planet at least... But to toss some examples:
Ironic Pirate said:
Fred Phelps would suffer the banhammer.
^Always a good option if you're considering assassination. "Dubya" would be a good one too, since he never paid for his crimes against humanity.
For more game-related people:
- Bobby Kotick.
- Whomever at Ubisoft came up with the "always on DRM".
- Whomever at Ubisoft ever thought that the aforementioned was a good idea.
Too tired to think of more... But honestly, the bodies would pile for miles.