Syagrius (430 – 486 or 487) is the last Roman official in Gaul, whose defeat by king Clovis I of the Franks is considered the end of Roman rule outside of Italy.

He came to this position through inheritance, for his father was Aegidius, the last Roman magister militum per Gallias.

Syagrius preserves his father's rump state between the Somme and the Loire around Soissons after the collapse of central rule in the Western Empire, a domain Gregory of Tours called the "Kingdom" of Syagrius.

Syagrius governs this Gallo-Roman enclave from the death of his father in 464 until 486, when he is defeated in battle by Clovis I.

Historians have mistrusted the title "rex Romanorum" that Gregory of Tours gave him, at least as early as Godefroid Kurth's dismissal in 1893 as a gross error.

The common consensus has been to follow Kurth, based on the historical truism that Romans hated kingship from the days of the expulsion of Tarquin the Proud; for example, Syagrius' article in the Prosopography of the Later Roman Empire omits this title, preferring to refer to him as a "Roman ruler (in North Gaul)".

However, S. Fanning has assembled a number of examples of rex being used in a neutral, if not favorable, context, and argues that "the phrase Romanorum rex is not peculiar to Gregory of Tours or to Frankish sources", and that Gregory's usage may indeed show "that they were, or were seen to be, claiming to be Roman emperors.