Dionysius, St., the Areopagite (i.e. judge of the Areopagus), according to Acts xvii. 34, a convert of St. Paul's; became bishop of Athens, and died a martyr in 95; was long regarded as the father of mysticism in the Christian Church, on the false assumption that he was the author of writings of a much later date imbued with a pantheistic idea of God and the universe.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Dionysius of Alexandria * Dionysius of Halicarnassus