The most creative gun in all of film SF goes, in my opinion, to a piece that was the center of attention in one episode of "Star Trek: Deep Space Nine", final season.
It was a rifle, an actual "bang" gun just as we thing of such things, except that somebody had stuck a teleporter device on the end of the barrel, and a sighting system that could see through walls.
So you'd aim "through" walls using a "depth control" in addition to regular aiming, and since the sight "knew" how "deep" you were looking, it would send that info to the teleporter at the moment of firing. The bullet would then go "through" as many walls as needed, or even *people*, without doing any damage until it got to the target...and without losing energy on the way.
Ohhhhhh ya.