Tonantius Ferreolus (also called Tonance Ferréol in modern French) (between about 440 and 450 – between 511 to after 517), was a vir clarissimus, or Gallo-Roman senator.
He lived in Narbo (modern Narbonne). Tonantius Ferreolus was a witness when Sidonius Apollinaris, then bishop of Clermont, between 461 and 467, sent a letter to his friend, Donidius, describing a visit he made, a "most delightful time in the most beautiful country in the company of Tonantius Ferreolus (the elder) and Apollinaris, the most charming hosts in the world". Tonantius was on the estates of his father when Sidonius Apollinaris visited between 461 and 467. As Sidonius relates, "at Prusianum, as the other (estate) is called, (the young) Tonantius and his brothers turned out of their beds for us because we could not be always dragging our gear about: they are surely the elect among the nobles of our own age".
He is known to be a friend and relative of Sidonius Apollinaris. He was the son of Tonantius Ferreolus and Papianilla. Papianilla is generally regarded as belonging to the Arvernian family of the Aviti, though in a generation senior to Sidonius' wife of the same name. The younger Tonantius' wife was an Industria living at Narbonne, born ca 450 to 460, married after 475, believed to have been daughter of Flavius Probus, Gallo-Roman Senator, and his wife Eulalia, (first cousin) of Sidonius Apollinaris. He was regarded as a senator even after the fall of the empire as was customary in Visigothic and Merovingian Gaul because his family had held the highest grades senatorial rank during the empire. No church offices are known for the younger Tonantius Ferreolus and he held no known positions under the Visigothic kings in the period leading up to the Battle of Vouille unless he continued in his father's position of Rector Galliarum. He may also have been appointed Defensor Pedensis (Royal official in the city of Pedena, now in Croatia) by Ostrogothic King Theodoric in 511. He had several siblings whose names are not preserved. There is some argument as to whether Ferreolus of Narbo referred to as husband of Industria and father of Firminus is Tonantius Ferreolus or a brother. Narbo was within the realm of the Visigoths and Tonantius Ferreolus almost certainly remained loyal to Euric and Alaric II prior to the Battle of Vouille. His involvement in that Battle is not known. Following the collapse of the Kingdom of Alaric, Southern Gaul including Narbo was briefly under the control of the Ostrogothic Kingdom in Italy. However, subsequent to the fall of the Burgundian Kingdom in the early 530's, the Austrasian Franks under Theodoric quickly took control of Burgundy and Provence as far as the Mediterranean and along the coast from at least Uzes on the west to the Italian border on the east leaving Narbo, except for one or two brief incursions, in Visigothic hands. The familial control of the See of Uzes, within whose borders much of the property of the Ferreolan villa of Prusianum was included, began during the time of Tonantius Ferreolus. Although Tonantius Ferreolus was not noted for any particular political or ecclesiastic initiative, his survival and that of his familia and properties following the loss of Gaul, first by the Roman Empire, and then the Visigoths, was to have important repercussions for the durability of Gallo Roman political identity, autonomy, laws and customs during the Merovingian and subsequent eras.