Research on private military and security companies (PMSCs) often groups distinct actors together, obscuring variation. I develop a new typology of PMSCs using k -means clustering, providing a more systematic approach than existing classifications, and assess how well prevailing conceptualizations capture variation across actors. Applying this typology to existing datasets, I reassess findings on conflict termination and show that results are largely driven by actors conventionally understood to be private security companies, while the effects of private military companies are more ambiguous. The study offers both a stocktaking of the literature and a new framework for analyzing PMSCs.