A slaughterhouse, also called abattoir ( (listen)), is a facility where animals are slaughtered, most often (though not always) to provide food for humans. Slaughterhouses supply meat, which then becomes the responsibility of a packaging facility.

Slaughterhouses that produce meat that is not intended for human consumption are sometimes referred to as knacker's yards or knackeries. This is where animals are slaughtered that are not fit for human consumption or that can no longer work on a farm, such as retired work horses.

Slaughtering animals on a large scale poses significant problems in terms of logistics, animal welfare, and the environment, and the process must meet public health requirements. Due to public aversion in many cultures, determining where to build slaughterhouses is also a matter of some consideration.

Frequently, animal rights groups raise concerns about the methods of transport to and from slaughterhouses, preparation prior to slaughter, animal herding, and the killing itself.