These amazingly realistic portraits were rendered in chalk and graphite by Scottish artist Paul Cadden. Apparently, he specializes in faces with lots of wrinkles personality. Shades of gray never looked so good!
http://paulcadden.deviantart.com/ --via BuzzFeed
I had a friend who used to make the most remarkable carvings of animals. They were incredibly detailed and looked exactly like real animals rendered in wood. He used to be irritated by people who called him an artist. He was adamant that he was a craftsman. Art, he would say, is easy because you don't have to get it "right". He was an old curmudgeon, but there you go.
http://www.juanfranciscocasas.com/
These are some of the best photo-realistic drawings I've seen.