XII Panegyrici Latini or Twelve Latin Panegyrics is the conventional title of a collection of twelve ancient Roman and late antique prose panegyric orations written in Latin. The authors of most of the speeches in the collection are anonymous, but appear to have been Gallic in origin. Aside from the first panegyric, composed by Pliny the Younger in AD 100, the other speeches in the collection date to between AD 289 and 389 and were probably composed in Gaul. The original manuscript, discovered in 1433, has perished; only copies remain.

Gaul had a long history as a center of rhetoric. It maintained its dominance of the field well into the 4th century. An early lead in the field was taken by the Aedui, early allies of Rome and eager to assimilate to the ways of their new rulers: Maenian schools were celebrated as early as the reign of Tiberius (r. AD 14–37). They continued to flourish into the days of Eumenius' grandfather, but were closed by the mid-3rd century.

There was some revival in the city in the late 3rd century, but after the establishment of Augusta Treverorum (modern Trier) as an imperial capital in the 280s, the orators began feeling jealousy for the imperial patronage enjoyed by the citizens of Trier. Despite the political and economic hegemony of the city, however, Trier failed to make any significant mark on the rhetoric of the period. Nixon and Rodgers suggest that it was simply too close to the imperial court. The surviving evidence (which might be prejudiced by Ausonius' Professors of Bordeaux) points to a shift from Autun and Trier as centers of the art in the Tetrarchic and Constantinian period, moving to Bordeaux later in the 4th century.

The panegyrics evince a familiarity with prior handbooks of rhetoric. Some have argued that Menander of Laodicea's treatises were particularly influential on the collection, and believed his precepts were used in the tenth panegyric. However, because so much of Menander's advice consisted of standard rhetorical procedure, the parallels adduced in favor of Menander as a model are insufficient to prove his direct use by the panegyrists. Other handbooks of rhetoric might also have had influence on the collection. Quintilian's Institutio Oratoria, for example, treats the subject of an oration's ancestry, parentage, and country in a manner similar to the panegyrics of 289, 291, 297, 310, 311, 321, and 389. In any case, the other panegyrics in the collection vary widely from Menander's schema. Parallels with other Latin orators, like Cicero and Pliny the Younger, are less frequent than they would have been if those authors had served as stylistic models.

The Latin of the panegyrics is that of a Golden Age Latin base, derived from an education heavy on Cicero, mixed with a large number of Silver Age usages and a small number of Late and Vulgar terms. To students of Latin in Late Antiquity, Cicero and Virgil represented the paragons of the language; as such, the panegyrists made frequent use of them. Virgil's Aeneid is the favorite source, the Georgics the second favorite, and the Eclogues a distant third. (Other poets are much less popular: there are infrequent allusions to Horace, and one complete borrowing from Ovid. When drawing from Cicero's body of work, the panegyrists looked first to those works where he expressed admiration and contempt. As a source of praise, Cicero's panegyric of Pompey in support of the Manilian law (De Imperio Cn. Pompei) was quite popular. It is echoed thirty-six times in the collection, across nine or ten of the eleven late panegyrics. Cicero's three orations in honor of Julius Caesar were also useful. Of these, the panegyrists were especially fond of the Pro Marcello; across eight panegyrics there are more than twelve allusions to the work. For vilification, the Catiline and Verrine orations were the prominent sources (there are eleven citations to the former and eight to the latter work).

Other classic prose models had less influence on the panegyrics. Pliny's Panegyricus model is familiar to the authors of panegyrics 5, 6, 7, 11, and especially 10, in which there are several verbal likenesses. Sallust's Bellum Catilinae is echoed in the panegyrics 10 and 12, and his Jugurthine War in 6, 5, and 12. Livy seems to have been of some use in panegyric 12 and Panegyric 8. The panegyrist of 8 must have been familiar with Fronto, whose praise of Marcus Aurelius he mentions, and the panegyrist of 6 seems to have known Tacitus' Agricola. The Aeduan orators, who refer to Julius Caesar in the context of Gaul and Britain, are either directly familiar with his prose or know of his figure through intermediaries like Florus, the historian. Panegyric 12, meanwhile, contains a direct allusion to Caesar's Bellum civile.

Accentual and metrical clausulae were used by all the Gallic panegyrists. All of the panegyrists, save Eumenius, used both forms at a rate of about 75 percent or better (Eumenius used the former 67.8 percent of the time, and the latter 72.4 percent). This was a common metrical rhythm at the time, but had gone out of style by the 5th century, when metrical considerations no longer mattered.

The collection comprises the following speeches: