The "San Francisco Chronicle" of August 3, 1879 described James O'Neill as "...a quiet gentleman of medium height, well-proportioned figure, square shoulders and stands very erect. He has black hair, black eyes, rather dark complexion, a black mustache, and a fine set of teeth which he knows how to display to advantage." Though not tall, James carried himself with a natural grace that gave him stature and he had, in addition to classical good looks, a magnetic stage presence. His son described him as being "broad-shouldered and deep-chested," with "a big, finely-shaped head, a handsome profile, deep-set, light-brown eyes."