Gratian or Gratianus (died 407) was a Roman usurper (407) in Roman Britain.
Following the death of the usurper Marcus, Gratian was acclaimed as emperor by the army in Britain in early 407. His background, as recorded by Orosius, was that he was a native Briton and one of the urban aristocracy. His rule coincided with a huge barbarian invasion that had afflicted Gaul, possibly with the connivance of Stilicho, the Emperor Honorius’s magister militum, who was concerned about the British usurpers. On the last day of December 406, an army of Vandals, Alans and Suebi (Sueves) had crossed the frozen Rhine. During 407, they spread across northern Gaul towards Boulogne, and Zosimus wrote that the troops in Britain feared an invasion across the English Channel.
The army wanted to cross to Gaul and stop the barbarians but Gratian ordered them to remain. Unhappy with this, the troops killed him after a reign of four months and chose Constantine III as their leader.
Geoffrey of Monmouth describes a similar character, named Gracianus Municeps, who is likely the same figure.
Gratian (/ˈɡreɪʃən/; Latin: Flavius Gratianus Augustus; 18 April/23 May 359 – 25 August 383) was Roman emperor from 375 to 383. The eldest son of Valentinian I, during his youth Gratian accompanied his father on several campaigns along the Rhine and Danube frontiers. Upon the death of Valentinian in 375, Gratian's brother Valentinian II was declared emperor by his father's soldiers. In 378, Gratian's generals won a decisive victory over the Lentienses, a branch of the Alamanni, at the Battle of Argentovaria. Gratian subsequently led a campaign across the Rhine, the last emperor to do so, and attacked the Lentienses, forcing the tribe to surrender. That same year, his uncle Valens was killed in the Battle of Adrianople against the Goths – making Gratian essentially ruler of the entire Roman Empire. He favoured Christianity over traditional Roman religion, refusing the divine attributes of the Emperors and removing the Altar of Victory from the Roman Senate.
Gratian was the son of Emperor Valentinian I by Marina Severa, and was born at Sirmium (now Sremska Mitrovica, Serbia) in Pannonia. He was named after his grandfather Gratian the Elder. Gratian was first married to Flavia Maxima Constantia, daughter of Constantius II. His second wife was Laeta. Both marriages remained childless. His stepmother was Empress Justina and his paternal half siblings were Emperor Valentinian II, Galla and Justa.
The Decretum Gratiani, also known as the Concordia discordantium canonum or Concordantia discordantium canonum, is a collection of Canon law compiled and written in the 12th century as a legal textbook by the jurist known as Gratian. It forms the first part of the collection of six legal texts, which together became known as the Corpus Juris Canonici. It was used by canonists of the Roman Catholic Church until Pentecost (May 19) 1918, when a revised Code of Canon Law (Codex Iuris Canonici) promulgated by Pope Benedict XV on 27 May 1917 obtained legal force.
It was about 1150 that Gratian, teacher of theology at the monastery of Saints Nabor and Felix and sometimes believed to have been a Camaldolese monk, composed the work entitled by himself, Concordia discordantium canonum, but called by others Nova collectio, Decreta, Corpus juris canonici, also Decretum Gratiani, the latter being now the commonly accepted name. He did this to obviate the difficulties which beset the study of practical, external theology (theologia practica externa), i. e. the study of canon law. In spite of its great reputation and wide diffusion, the Decretum has never been recognized by the Church as an official collection.
Gratian can refer to: