As computer users, we have all become familiar with the term "icon." It's the little thingie we click on when we want the computer to do something. Actually they're little more than fancy pushbuttons for our mouse-clicks where descriptive words defining what happens would be too long and complex. Some might also deem them an assault on literacy. In art, the church once relied on icons for much the same reason--the illiteracy of the masses. The Greek letters Chi and Rho, used to refer to Christ, are an example. Later the use of the fish and still later the cross came to symbolize Christianity. As art and Christianity progressed hand in hand, the image of Christ became much more realistic and complex. Today, we know him as a bearded young man of medium height, fairly athletic in build, sometimes with Aramaic features, usually seen more light complexioned than was likely the case, and always with a benign, loving expression.
No one artist is likely to have defined this image, in that it seems to have gradually evolved over a period of centuries. If one looks back over Christian Art far enough, there are some depictions of Jesus that seem to have been created before our present-day icon/image was set in stone (or wood or pigment, whatever). One can be found in a lunette of the atrium leading to the church of San Vitale in Ravenna, Italy (one of the oldest in Christendom). It dates from sometime in the period 494 to 520 AD. It's not a painting, but a mosaic not unlike the much more famous mosaics in the church itself, which depict the Roman emperor, Justinian, and his court. It is Byzantine in style, and totally unlike any picture of Christ you've ever seen before.
He stands in an arch, his right foot on a Roman lion, his left on a satanic serpent. Behind him are two rolling hills, around his head a halo, over his right shoulder is slung a slender cross held not unlike a farmer might carry a hoe. In his left hand he displays an open book with a Latin text. He is portrayed not as the good shepherd (as in the earlier Roman catacombs), but as a conquering monarch, young, unbearded, eyes large and stylized, hair braided, dressed in a knee-length Roman "kilt," a regal robe slung over his shoulder, held by a jeweled clasp, his feet shod with Roman military footwear. The predominant colors of the mosaic tiles are gold, brown, red, black, and green. Were it not for the title, "Jesus of Nazareth as Christus Imperator" one might mistake the figure for a young prince of perhaps St. George of dragon slaying fame. One has to wonder why THIS image lost out to what we know today. Maybe it was the kilt.