There are seven special angels who stand before the throne of God. We know the names of three of them. They are Saint Michael, Saint Gabriel and Saint Raphael.
The greatest and most powerful of all God's angels is Saint Michael. His name means Who is like to God? This was the challenge he issued to Lucifer when Lucifer offended God and was hurled by Saint Michael out of Heaven and into hell. It was Saint Michael who appeared to Abraham to forbid him to sacrifice his son Isaac. Saint Michael brought the plagues to Egypt. Saint Michael led the Israelites on their journey to the Promised Land and fought with Lucifer for the body of Moses. Saint Michael led Josue into the Promised Land. Saint Michael delivered the three young men from the fiery furnace. Saint Michael sent Habacuc to feed Daniel in the lions' den. Saint Michael escorted the Blessed Virgin Mary into Heaven on the day of her Assumption. Saint Michael is the Guardian Angel of the Pope. He is the special protector of the Church. He is the special angel of the Blessed Sacrament. He leads the souls of the Just into Heaven when they die. He is invoked in the lovely prayer: "Holy Archangel Michael, defend us in the battle. Be our protection against the wickedness and snares of the devil…" Saint Gregory the Great was the Pope specially devoted to Saint Michael. Saint Michael appeared to Saint Joan of Arc and helped her in her battle against the English. He also appeared in France, in Normandy, in 709. A beautiful shrine was built to him on a hill there, the still famous Mont Saint-Michel.
Saint Michael also appeared in a cave in southern Italy - not far from Padre Pio's place in San Giovanni Rotondo.
In fact Padre Pio's place was initially visited by pilgrims - not to see Padre Pio - but on their way to see the cave of St Michael.
Here's more on St Michael...
http://www.traditioninaction.org/SOD/j093sdMichael_9-29.htm