The Dionysius Areopagite was the first bishop of Athens according to St. Dionysius of Corinth, a 3rd century writer. St. Basil's Menology says he was burned to death during Domitian's persecution about 95. His name has become so confused with that of St. Denis that his feast day has been transferred from October 3 to October 9. His cult developed in the 9th century. His supposed writings (four treatises and ten letters on mysticism, which were actually by the pseudo-Dionysius) were the basis for medieval mystic theology. The pseudo-Dionysius probably wrote c. 500 AD. Dionysius the Areopagite was converted in Athens by St. Paul (Acts 17).

The Martyrology of Jerome mentions St. Dionysius on October 9, together with Rusticus and Eleutherius, assumed by later writers to be Denis's priest and deacon. The Denis is presumed to be the bishop-martyr of Paris, one of the seven missionary bishops sent from Rome to convert Gaul. He was martyred between 250-258 AD.

Writing in the 6th century, St. Gregory of Tours tells the story of these three martyrs. Born in Italy, Denis was sent with six other bishops to Gaul in 250 as missionaries and became the first bishop of Paris. He was so effective in converting the inhabitants around Paris that he was arrested with his priest, St. Rusticus, and deacon, St. Eleutherius, and imprisoned. The three of them were beheaded on October 9 in Montmartre (Martyrs' Hill) near Paris during Decius's persecution. Their bodies were rescued from the River Seine, and a chapel built over their tomb later became the Benedictine Abbey of Saint-Denis (Delaney).

Roeder claims that the deacon Eleutherius was beheaded in 286 and is shown as a deacon carrying his head. He is invoked against headache, frenzy, and strife. Venerated in Salzburg and Paris (Roeder).

In 1215 Pope Innocent III translated the presumed relics of the Areopagite to the popular Basilica of St. Denis in Paris. This also added additional confusion to the stories of the three saints.

St. Denis was one of the Fourteen Holy Helpers (feast 8-8). During the Middle Ages, especially in France and Germany these saints were credited with particularly efficacious intercessory power. All had/have also individual feast days. Most are non-existent, or shadowy figures of early Christianity popularized by embroidered tales. Their special powers of intercession are connected with incidents in their stories. For example, St. Denis is shown with his head in his hands; therefore, he is invoked against diabolic possession, headache, rabies, frenzy, and strife.

For more information St. Denis and other confused, interesting stories, see Lancelot Sheppard's The Saints Who Never Were, Dayton, OH: Pflaum Press, 1969. Also, Dionysius the Areopagite, The Divine Names and Mystical Theology, tr. C. E. Rolt, London, 1920.