R v Dudley and Stephens (1884) 14 QBD 273, DC is a leading English criminal case which established a precedent throughout the common law world that necessity is not a defence to a charge of murder. The case concerned survival cannibalism following a shipwreck, and its purported justification on the basis of a custom of the sea.

Human cannibalism is the act or practice of humans eating the flesh or internal organs of other human beings. A person who practices cannibalism is called a cannibal. The meaning of "cannibalism" has been extended into zoology to describe animals consuming parts of individuals of the same species as food.