Were centurions officers or NCOs?

Should Roman centurions be understood as officers or as non-commissioned officers?

They were a mixture of both: Roman command structures combined duties and social ranks differently from a modern army.

Forcing the Roman legion into a modern officer-versus-NCO model obscures how its hierarchy worked. Centurions and optiones led units of varying size, while tribunes, legates, and socially defined cavalry ranks formed a combined structure. A maniple could contain roughly 120 to 200 soldiers under a senior and junior centurion with corresponding optiones. Legionaries also received informal responsibility for small detachments, providing practical lower-level leadership without a standardized NCO corps. The example of an eight-man group shows how small units could still acquire working leaders without a modern rank ladder.