Saint Martin of Tours

El Greco, Saint Martin and the Beggar, c. 1597-1599, oil on canvas, 193.5 x 103 cm, National Gallery of Art, Washington DC

Martin was a soldier in the Roman army who converted to Christianity.  He encountered a peastant one day and gave him half his cloak; that night, he dreamt that Jesus wore it.  He considered it a calling and left the military to devote his life to preaching Christianity.  

While the most common depiction of him is with the beggar, he also spent 25 years as a bishop, and thus is sometimes depicted with a mitre and a crosier.