The diocese of Dionysiana (in Latin: Dioecesis Dionysianensis) is a suppressed and titular see of the Roman Catholic Church.
The Diocese of Dionysos, was centered on a Roman town of the Roman province of Byzacena ( in today's Tunisia) during late antiquity.
There are three known bishops of this diocese during antiquity, which is one of the oldest in Roman North Africa.
The diocese ceased to effectively function with the ArabâÂÂByzantine wars in 698.
Since 1925 Dionysius now survives as a titular bishopric and the current bishop is Gary W. Janak, auxiliary bishop of San Antonio, Texas.