Change my mind

Russel Crowe's 'Marcus Decimus Meridius' is one of the best depictions of a Roman in a movie. Everything, from his cut and right way of speaking to his look, just oozes Roman (from what I have gathered after almost a lifetime of literature, media and podcasts)

Lucius vorenus is a close second, but it is not a movie so there is more time for character development.