Merena

Merena was a military officer of the Sassanid Empire during the reign of Shapur II in the 4th century. He was a cavalry commander in the Sassanid army in the course of the Roman-Persian Wars soon after the Battle of Ctesiphon in 363, which took place outside the Sassanid capital Ctesiphon in what is now modern-day Iraq. He was among those killed at the subsequent Battle of Samarra, a few hours before the death of the Roman emperor Julian.

Source

 * Ammianus Marcellinus, History 25.1.11, 25.3.13