Seventeenth century scholastics had a rich debate about the ontological status and nature of lacks, negations, and privations. Realists in this debate posit irreducible negative entities responsible for the non-existence of positive entities. One of the first scholastics to develop a realist position on negative entities was Thomas Compton Carleton. In this paper I explain Carleton's theory of negative entities, including what it is for something to be negative, how negative entities are individuated, whether they are abstract or concrete, and (...) how they affect their subjects. I argue that for Carleton, negative entities are conceived as spatially extended simples that affect their subjects by means of spatial overlap. I also show how Carleton responds to some theological worries about his realism concerning negative entities. (shrink)