Saint Patrick was a fifth-century Romano-British Christian missionary and bishop in Ireland. Known as the "Apostle of Ireland", he is the primary patron saint of Ireland, along with saints Brigit of Kildare and Columba. (taken from Wikipedia)
Here's a little known fact about Saint Patrick: While he is the patron saint of Ireland, he wasn't actually born there! Saint Patrick was born (under the name "Maewyn Succat") in Brittania.
Have an awesome Saint Patrick's Day, Everybody!