Saint Denis (also called Dionysius, Dennis, or Denys) is a Christian martyr and saint.
In the third century, he was Bishop of Paris.
He was martyred in connection with the Decian persecution of Christians, shortly after A.D. 250. After his head was chopped off, Denis is said to have picked it up and walked ten kilometres (six miles), preaching a sermon the entire way, making him one of many cephalophores in hagiology.
He is venerated in the Roman Catholic Church as patron saint of Paris.
Source: Wikipedia.