In person he was large and robust; of a stature somewhat above the common size; broad in the shoulders and chest, and proportionable in the rest of his frame. He used his left hand more readily and with more force than his right; and his joints were so strong, that he could bore a fresh, sound apple through with his finger, and wound the head of a boy, or even a young man, with a fillip. He was of a fair complexion, and wore his hair so long behind, that it covered his neck, which was observed to be a mark of distinction affected by the family. He had a handsome face, but it was often full of pimples. His eyes, which were large, had a wonderful faculty of seeing in the night-time, and in the dark, for a short time only, and immediately after awaking from sleep; but they soon grew dim again. He walked with his neck stiff and upright; generally with a frowning countenance, being for the most part silent: when he spoke to those about him, it was very slowly, and usually accompanied with a slight gesticulation of his fingers. All which, being repulsive habits and signs of arrogance, were remarked by Augustus, who often endeavoured to excuse them to the senate and people, declaring that "they were natural defects, which proceeded from no viciousness of mind." He enjoyed a good state of health, without interruption, almost during the whole period of his rule; though, from the thirtieth year of his age, he treated himself according to his own discretion, without any medical assistance.

In regard to the gods, and matters of religion, he discovered much indifference; being greatly addicted to astrology, and fully persuaded that all things were governed by fate. Yet he was extremely afraid of lightning, and when the sky was in a disturbed state, always wore a laurel crown on his head; because it is supposed that the leaf of that tree is never touched by the lightning.