Flavius Julius Crispus (; 300 – 326) was the eldest son of the Roman emperor Constantine I, as well as his junior colleague (caesar) from March 317 until his execution by his father in 326. The grandson of the augustus Constantius I, Crispus was the elder half-brother of the future augustus Constantine II and became co-caesar with him and with his cousin Licinius II at Serdica, part of the settlement ending the Cibalensean War between Constantine and his father's rival Licinius I. Crispus ruled from Augusta Treverorum (Trier) in Roman Gaul between 318 and 323 and defeated the navy of Licinius I at the Battle of the Hellespont in 324, which with the land Battle of Chrysopolis won by Constantine forced the resignation of Licinius and his son, leaving Constantine the sole augustus and the Constantinian dynasty in control of the entire empire. It is unclear what the legal status was of the relationship between Crispus's mother Minervina and Constantine; Crispus may have been an illegitimate son.
Crispus's tutor in rhetoric was the Late Latin historian of Early Christianity Lactantius. After his elevation to imperial rank, at which point he was also entitled princeps iuventutis ("Prince of Youth"), the Latin rhetorician Nazarius composed a panegyric preserved in the Panegyrici Latini, which honoured Crispus's military victories over the Franks in . Crispus was three times Roman consul, for the years 318, 321, and 324.
According to the Latin histories of Ammianus Marcellinus and Aurelius Victor, after a trial whose real circumstances are mysterious, Constantine executed Crispus at Pola (Pula) in 326. His stepmother Fausta was also put to death, and the Late Greek historian Zosimus and the Byzantine Greek writer Joannes Zonaras wrote that Constantine had accused Crispus of incest with her. After his death, Crispus was subjected to damnatio memoriae.
Early life
While Crispus’ year of birth is nowhere outright stated, he must have been born before 307. In that year, his father Constantine was married to Maximian’s daughter Fausta, so his mother Minervina was either dead or had been set aside.
Constantine entrusted his eldest son’s education to Lactantius, one of the most important Christian teachers of that time. Soon afterwards, Constantine had his wife Fausta killed also, according to several sources in a hot bath or bathroom. Both Crispus and Fausta suffered damnatio memoriae, their names being erased from inscriptions.
The reason for these deaths remain unclear. The accounts of Zosimus and Zonaras say that Crispus was executed due to suspicions that he was involved in an illicit relationship with Fausta, but some scholars have been skeptical of this explanation. For instance, T. D. Barnes argues that as Crispus was based at Trier, and Fausta at Constantinople, they would not have had the opportunity to have an affair. While Hans Pohlsander considers Barnes’ argument to be invalid on the basis that Crispus was in the East for long enough, he suggests that the similarity of Zosimus' story to the myth of Phaedra and Hippolytus makes its veracity doubtful. He does, however, note that Constantine passed multiple laws on adultery in the same year, which may have been related to the deaths of Crispus and Fausta. On the other hand, David Woods accepts the belief that the two were thought to have had a relationship, while suggesting that they were not actually executed. According to his theory, Crispus was exiled to Pola as a punishment for his adultery and committed suicide by poison there, and Fausta's death was caused by an attempt to induce abortion to get rid of an unwanted pregnancy that resulted from her affair.
Pohlsander observed that Crispus “must have committed, or at least must have been suspected of having committed, some especially shocking offense to earn him a sentence of death from his own father.” and Tarquinio Galluzzi's 1633 Defense of Crispus. The play was adapted for the French stage by François de Grenaille as L'Innocent malhereux (1639) and by Tristan l'Hermite as La Morte de Chrispe ou les maleurs du grand Constantine (1645). It was performed as an opera in Rome (1720) and London (1721), where it was entitled, Crispo: drama, not to mention Donizetti's 1832 opera Fausta. The story is also retold and embellished in chapter 31 of Sir Walter Scott's novel Count Robert of Paris. When Evelyn Waugh reworks the story in his novel Helena (1950), Crispus is innocent.