Martinian (emperor)
| Sextus Marcius Martinianus | |
|---|---|
 Follis of Martinianus | |
| Reign | July - September 18 324 (nominally as Augustus in the west, with Licinius as Augustus in the east) |
| Predecessor | Constantine I |
| Successor | Constantine I |
Sextus Marcius Martinianus (d. 325) was Roman Emperor from July to September 18 324. He had been appointed co-emperor by Licinius.
In 324 the second civil war between Licinius and Constantine I was in full swing, and Licinius was losing. Because of this war he decided to replace Constantine (in name only) as western Augustus. As his replacement he named Martinianus, then a magister officiorum at his court, as co-emperor some time after the Battle of Adrianople on July 3 324.
Licinius sent Martinianus to Lampsacus (in the Dardanelles) to attack Constantine as he crossed the Bosporus. Martinianus apparently had little success, for on September 18 Licinius was defeated for the last time in the Battle of Chrysopolis. Martinianus was killed on orders from Constantine, while Licinius was at first spared.