Diadumenian, Roman emperor (d. 218)

Diadumenian (; Latin: Marcus Opellius Antoninus Diadumenianus; 14 September 208 – June 218) was the son of and co-ruler with Roman Emperor Macrinus. His mother was Nonia Celsa, whose name may be fictitious. Diadumenian became Caesar in May 217. Elagabalus revolted in May 218, and Diadumenian was elevated to co-emperor. After Macrinus was defeated in the Battle of Antioch, on 8 June 218, Diadumenian was sent to the court of Artabanus IV to ensure his safety; however, he was captured and executed along the way, in late June.