A handy tool for global domination, frequently utilized by mad scientists, international megalomaniacs, supervillains, and invaders from Mars. The best ones are powered by atomic energy and fire lethal lasers which annihilate all life forms. Less effective weapons might be powered by chocolate milk, or might only destroy aardvarks. Do it right the first time, and the world is yours.
Addendum: Transitional Man sez: "While in Air Force ROTC in the late fifties, my father saw a film of an Army death ray. It was carried by a semi and would kill a rabbit at 100 yards. Of course they had to cage the rabbit so the beam would hit. I have no idea how it worked." Okay, I'm all in favor of death rays for world conquest, international blackmail, and random murders of television news pundits, but killing cute widdle bunnies? THIS IS TOO MUCH!