An unpainted face

When we visualize Vincent van Gogh we see one of his painted self-portraits in our mind's eye. Above is a photograph of him at age 18. It is the only photograph that is known for sure to be of him. 

At the time he was training with the firm Goupil & Cie in The Hague to be an art dealer. Curiously, considering his latter problem selling his own paintings, once out of training he was successful at his job. However, a failed romance and his religious passion were soon to send him down the path that led to him becoming an artist.

This is believed to be a picture of van Gogh at the age of 13, although its authenticity is disputed. 

Finally, some argue that this is a photo of van Gogh as an adult (for some reason my version has been flipped horizontally). The picture has been carefully  analyzed and compared to his self portraits. Some experts think he used the camera obscure technique to trace the lines of his face before painting his later self-portraits and the features have been carefully lined up as a test. It certainly looks like a match, but there is still debate as to whether it is actually him of not.

You can read about that debate at Neatorama's post Rediscovering Van Gogh.