Mass killing is a concept which has been proposed by genocide scholars who wish to define incidents of non-combat killing which are perpetrated by a government or a state. A mass killing is commonly defined as the killing of group members without the intention to eliminate the whole group, or otherwise the killing of large numbers of people without a clear group membership.

Walter Haddon LL.D. (1515–1572) was an English civil lawyer, much involved in church and university affairs under Edward VI, Queen Mary, and Elizabeth I. He was a University of Cambridge humanist and reformer, and was highly reputed in his time as a Latinist. His controversial exchange with the Portuguese historian Jerónimo Osório attracted international attention partly on account of the scholarly reputations of the protagonists.

Mass killing is a concept which has been proposed by genocide scholars who wish to define incidents of non-combat killing which are perpetrated by a government or a state. A mass killing is commonly defined as the killing of group members without the intention to eliminate the whole group, or otherwise the killing of large numbers of people without a clear group membership. The term mass killing is used by a number of genocide scholars because the term genocide (its strict definition) does not cover mass killing events in which no specific ethnic or religious groups are targeted, nor does it cover events in which perpetrators do not intend to eliminate whole groups or significant parts of them. Genocide scholars use different models in order to explain and predict the onset of mass killing events. There has been little consensus nor has there been a generally-accepted terminology, prompting one scholar to describe comparative attempts a failure. Genocide scholarship rarely appears in mainstream disciplinary journals.