The Last Supper - Leonardo da Vinci

Many painters of his time repeated the figures from one work to the next if they liked them. The models were the same, no matter who they were, but Leonardo had a different way of working. He would study the nature and appearance of the figure he wanted to paint and then, when he knew what he wanted, he would go to a place where he was likely to find people with those characteristics. He would take notes of their faces, movements and attitudes, and would not let go until he found the model that matched what he had in mind.

In the case of the Last Supper, he chose his models with particular care. Legend has it that Leonardo found a young man for Jesus Christ who was exactly what he was looking for. The chosen one evoked both life and spiritual strength. For six months he modelled for him.

Time passed and, although the work was almost finished, the prior of Santa Maria delle Grazie became impatient and complained that Judas still had no face.
Leonardo went to the prison, where the condemned men were being held, to see if he could find his model. There he saw a man who had committed many atrocities and was to be executed. It was exactly what he was looking for, his face reflected evil, hatred and wickedness, he had in his eyes a hardness and coldness perfect for Judas the traitor.