Romanos (or Romanus) IV Diogenes is a member of the Byzantine military aristocracy who, after his marriage to the widowed empress Eudokia Makrembolitissa, is crowned Byzantine emperor and reigns from 1068 to 1071.

During his reign he is determined to halt the decline of the Byzantine military and to stop Turkish incursions into the Byzantine Empire, but in 1071 he is captured and his army routed at the Battle of Manzikert.

While still captive he is overthrown in a palace coup, and when released he is quickly defeated and detained by members of the Doukas family.

In 1072, he is blinded and sent to a monastery where he dies of his wounds.