Here is the earliest known depiction, from the catacombs of Comodilla, dating from the fourth century:
Here is an eleventh century painting:
Neither of these is shocking, or seems sacrilegious in any way. Both show a somber-looking man.
Early medieval depictions of Jesus tend to put him in royal garb. This isn't all that surprising, as royalty was looked at back in those days with almost holy reverence. Those artists might have considered it insulting to show him in anything less:
Later medieval artists tended to put more of their own personal stamp on their work. Here is Christ as a Man of Sorrows, by Andrea Mantegna, who seemed to want to depict Christ as a man who hit the gym regularly and had a farmer's tan:
And here is The Baptism of Christ by Piero della Francesca, from 1449, a depiction with homoerotic overtones:
As Christianity spread, local artists tended to depict Christ in their own ethnicity, understandably enough. Here is a Chinese painting, Christ and the Rich Man:
And here is a Haitian painting of the Baptism of Christ:
Westerners may laugh at these Chinese and black Jesuses, but western portrayals showing an Anglo-Saxon Christ are also misleading:
More recently, the efforts of artists to depict him with an almost otherworldly saintliness have led in some weird directions. The artist who produced this painting seemed to envision Jesus as a beautiful woman wearing eyeliner and a beard:
Of course, all artists are faced with a certain quandary. Should they depict Jesus as careful coifed, with a neatly trimmed beard and hair that looks as if he's fresh from the salon, which might indicate vanity? Or should they depict him as looking more like a homeless guy, which might be viewed as disrespectful? This artist opted for the former look:
Jesus has evidently just walked on water here, but his freshly scrubbed face looks more as if he has just bathed in it. Cleanliness evidently is next to godliness.
Here's a Jesus who looks a little like a goody two shoes:
Here's a hipster Jesus-as-party-animal from the anti-Christian 1999 film Dogma:
And here's a triptych of the Mormon Jesus:
On the left, Jesus dressed by Bed, Bath, and Beyond; in the middle, Jesus-as-action-hero; and on the right, Jesus-with-a-sense-of-humor.
I'm not trying to be sacrilegious; these are all comments on the artists, not Jesus himself. But what did Jesus look like? He was, after all, a Jew, so probably looked Semitic. He was intelligent -- had a high IQ, in modern parlance. He had to have been charismatic, to attract so many followers. And as a natural leader of men, it's not unlikely that he was tall.
So perhaps he looked like this intelligent, 6' 5" Jew:
Or, perhaps he had a swarthier cast to his features. Here's another 6' 5" Semite who attracted many followers:
(Surprisingly, bin Laden often wore a strangely beatific expression.)
Okay, now I'm being sacrilegious. But the fact is, Jesus probably did bear more resemblance to Howard Stern or Osama bin laden than he did to the blue-eyed blond so frequently depicted in the past century.
Either way, the larger point here is that Christians are a tolerant people. They will not attack you no matter how you depict their leader -- unlike members of another religion. Christians even bend over backward to accommodate other religions. And it's that tolerance of others' intolerance that will be their downfall.