The Hadamar killing centre was a killing facility involved in the Nazi involuntary euthanasia programme known as Aktion T4. It was housed within a psychiatric hospital located in the German town of Hadamar, near Limburg in Hessen.

Involuntary euthanasia, typically regarded as a type of murder, occurs when euthanasia is performed on a person who would be able to provide informed consent, but does not, either because they do not want to die, or because they were not asked.