Several people in history have been known by the name Dionysius:

• Dionysius of Syracuse, a tyrant
• Dionysius the Elder, a Greek mythological figure
• Dionysius the Areopagite, a citizen of Corinth who was converted by Paul of Tarsus
• Pseudo-Dionysius the Areopagite, identified by some with a Georgian theologist Peter the Iberian (411 - 491), author of Corpus Areopagiticum
• Dionysius Exiguus, a Dacian monk who helped set the date of some Christian holidays
• Dionysius Halicarnassensis, a Greek scholar of the Roman period
• Dionysius Telmaharensis, a former head of the Syrian Jacobite Church
• Pope Dionysius
• Saint Denis, Bishop of Paris, martyr (died ca. 250)
• Dionysius the Wise, the Russian medieval icon-painter
• Dionysius Lardner, an Irish scientific writer
• Benjamin Musaphia, Jewish doctor, scholar, and kabbalist (1606-1675), who sometimes called himself Dionysius.

The Name Dionysius is sometimes confused with Dionysos, the Name of a Greek deity.