I am now the proud owner of a coin of the very rare and very valuable late Roman usurper Jovinus (not Jovianus). He ranks up there with my Libius Severus, Majorian, and my Placidia in rarity.
His silver issues (these and gold make up his only coins) rank 9 on the 1 to 9 scale used on ERIC's absolute rarity list, and on the relative scale he falls in spot #159 out of 202 rulers on the list. So as a serious collector of very late Roman coins, a coin of Jovinus was a must have for me.
Jovinus, Western Roman Empire
AR siliqua
Obv: D N IOVIN-VS PF AVG, Pearl-diademed, draped, and cuirassed bust right
Rev: VICTOR-IA AVGG, Roma seated left on stylized cuirass, holding Victory on globe and reversed spear
Mint: Lugdunum (Mintmark: SMLDV); struck 411-413 AD
Ref: RIC X 1716

Jovinus was a Roman senator from Gaul living in the early 5th century AD, a time rife of wannabe emperors and larger and more threatening marauding bands of barbarians. It is 411 AD. Rome had recently been captured and ransacked for the first time in eight centuries, Britain had been abandoned by the Romans for good, and barbarian tribes were beginning to establish themselves on former Roman territory. In response to the crisies happening on the continent, the Romano-British in 407 had elected one of their own to be emperor, the usurper Constantine III. He ruled in opposition to the legitimate emperor Honorius and was briefly recognized by him, but Constantine III was eventually forced to abdicate and shortly after was executed.
Rebelling Roman troops then proclaimed Jovinus as emperor in 411 in the city of Mogontiacum (Mainz), with the Gallic nobility backing him as well, and as a sign of the increasing influence the barbarians were having on the Roman Empire, Jovinus was also supported by the kings of both the Burgundians and the Alans, Gundahar and Goar, respectively. The usurper allowed the Burgundians to settle on the west side of the Rhine in Roman territory. Jovinus managed to rule Gaul as emperor for two years.
The Visigoths under King Ataulf alligned with Jovinus as well, but this relationship quickly turned sour when Ataulf had Visigoth-renegade and Jovinus-supporter Sarus killed. Things further went south when in 412, Jovinus appointed his brother Sebastianus as his co-emperor without discussing the move with Ataulf. The Visigothic king then switched his allegiance to Honorius and in 413 had his forces attack those of Jovinus and Sebastianus. Sebastianus was captured, turned over to Romans loyal to Honorius, and executed. Jovinus fled but was later captured and executed as well. His head was placed on display on the walls of Ravenna along with the head of Sebastianus, and both heads were sent to Carthage to be displayed there as well, along with the heads of four other usurpers (there were a lot of usurpers under Honorius).