A staple gun or powered stapler is a hand-held machine used to drive heavy metal staples into wood, plastic, or masonry. Staple guns are used for many different applications and to affix a variety of materials, including insulation, house wrap, roofing, wiring, carpeting, upholstery, and hobby and craft materials. These devices are also known as a trigger tacker

Staple guns may be driven by muscle power, electricity (from domestic power or from batteries) or compressed air. Power staple guns can set staples at a somewhat quicker rate than hand-powered models, but their main advantage is that they can be used continuously for hours with comparatively little fatigue.

Some staple guns have a long nose that allows the staples to be applied into recessed corners. Another special feature may be wire guides for wiring to ensure that the staples will not pierce the wire. The "forward action" staple gun has a handle that points toward the trigger end, in the opposite direction of the traditional staple gun. These tools are easier to squeeze and better place pressure at the front of the tool where the staple is ejected. The first so called "forward action" staple gun was introduced about 1934.