A knacker (), knackerman or knacker man, is a job title used for the centuries-old trade of persons responsible in a certain district for the removal and clearing of animal carcasses (dead, dying, injured) from private farms or public highways and rendering the collected carcasses into by-products such as fats, tallow (yellow grease), glue, gelatin, bone meal, bone char, sal ammoniac, soap, bleach and animal feed. A knacker's yard or a knackery is different from a slaughterhouse or abattoir, where animals are slaughtered for human consumption. Since the Middle Ages, the age-old occupation of "knacker man" was frequently considered a disreputable occupation, and subsidiary to their occupation were often also commissioned by the courts as public executioners. In most countries, knackery premises are government licensed and regulated by law.