In his Categories, Aristotle details the kinds of being that exist, along with what can be understood and predicated of existing things. Most notably within this work, Aristotle advances a set of ten, top-level categories that can be used to classify all kinds of being. Even today, the influence of the Categories is felt in many domains, particularly in knowledge organization (KO). Here, Aristotle’s Categories bear deep, long-standing connections with works examining categorization, subject analysis, and theory of classification. Though its relation to ontology might seem obvious, connections to KO perspectives on knowledge organization systems (KOSs) and ontological modeling are curiously lacking. The aim of this work is to offer a re-examination of the Categories as a KOS, particularly through the lens of the KO field’s understandings of ontology. Utilizing Zeng’s classification of KOSs as a theoretical framework, this study draws parallels between the first two sections of the Categories and the defining features of ontologies and offers an initial ontological model of this work. The results of this re-examination stand to offer a new view of a fundamental work in the KO canon, draw further connections between past and present perspectives in KO, and further contribute to the theoretical grounding of contemporary KOS research and practice.