Diadumenian - Augustus of Imperium Romanum from 218 to 218
Marcus Opellius Antoninus Diadumenianus Augustus was the son of the Roman Emperor Macrinus, and served his father briefly as Caesar (May 217–218) and as Augustus (in 218).

The name stems from him being born with a caul that formed a 'diadem'.

Diadumenian had little time to enjoy his position or to learn anything from its opportunities because the legions of Syria revolted and declared Elagabalus ruler of the Roman Empire. When Macrinus was defeated on 8 June 218, at Antioch, Diadumenian's death followed his father's.
Diadumenian
Emperor Diadumenian of the Roman Empire

(1) Diadumenian 217-218 AD
Obverse: bare head right; K M OΠΠEΛ ANTΩNI ΔIAΔOVMENIANOC
Reverse: Homonoia facing, head left, holding patera and cornucopia; VΠ AΓPIΠΠA NIK_OΠOΛITΩN ΠΡOCIC / TΡΩ
Ref: AMNG I 1817f. (Var.); Varbanov 3641
(2) Diadumenian 217-218 AD
Obverse: Κ Μ ΟΠΠΕΛ ΑΝΤΩΝΙ ∆ΙΑ∆ΟΥΜΕΝΙΑΝΟC, Bare bust of Diadumenian facing right
Reverse: VΠ ΑΓΡΙΠΠΑ ΝΙΚΟΠΟΛΙΤΩΝ ΠΡΟC ICT, City-gate flanked by two towers and with a taller third tower rising from center (or from behind)
Ref: Varbanov 3639
(3) Diadumenian 217-218 AD
Obverse: draped and cuirassed bust right; M OP DIADVMENIAN[V?] CAE
Reverse: Serapis head right wearing modius; COL·P·FL·AV_F·C·CAESAR
Ref: Kadman 78; SNG ANS 801; Rosenberger...
(4) Macrinus | Diadumenian 217-218 AD
Obverse:
Reverse:
Ref: None provided