This work explores the phenomenon of non-being (mé onta) and develops the foundations of meontology through a systematic classification of its various forms. The author analyzes the relationship between non-being, temporality, intentionality, and the ontological structure of reality. Ten specific categories are identified: non-being as the past, the future, the internal or non-objective, and the purely thought-constructed. Furthermore, the text examines non-being from the perspectives of logical impossibility, temporal non-simultaneity, and ontological transience. A key contribution is the conceptualization of non-being as potentiality (the possible) and as a normative requirement (that which ought to be). The analysis culminates in a reflection on non-being within event-based ontology, where an entity is defined as a process that is always partially non-existent. This systematic approach radically challenges traditional metaphysical focuses on fixed presence, emphasizing a dynamic nature of reality that necessarily incorporates elements of non-being as constitutive factors of events and meaning within both human experience and the world.