Saint Juan Diego, who originally went by the name of Cuauhtlatoatzin, was a sixteen century Mexican
who was beatified for his work in spreading Catholicism
Little is known of his personal life, except that he was born around 1480, and did agricultural work, but it is said, that in 1531, having already been converted himself by the Spanish, he saw a vision of the Virgin Mary. He was instructed to build a church, and recieved the miracle of his uncle's healing.
From there he went forth to convert much of Mexico. Unfortunately, there is doubt as to whether he actually existed! There are many theories that make him out to be merely an invented figurehead for the Catholic Church in Mexico.
What is certain that as a 50 year old in 1531, he was not the typical saint. The revalation to one so old is not common amongst the Catholic saints, and this possibly provides evidence against his fabrication.