Known for his tireless charity work, particularly for the sick and the poor, and consequently has many hospitals named after him. From here:
Born at Montemor o Novo, Portugal, 8 March, 1495, of devout Christian parents; died at Granada, 8 March, 1550. He is said to have been granted the vision of the Infant Jesus, Who bestowed on him the name by which he was later known, John of God, also bidding him to go to Granada. There he was so deeply impressed by the preaching of Blessed John of Avila that he distributed his worldly goods and went through the streets of the city, beating his breast and calling on God for mercy. For some time his sanity was doubted by the people and he was dealt with as a madman, until the zealous preacher obliged him to desist from his lamentations and take some other method of atoning for his past life. Returning to Granada, he gave himself up to the service of the sick and poor, renting a house in which to care for them and after furnishing it with what was necessary, he searched the city for those afflicted with all manner of disease, bearing on his shoulders any who were unable to walk.