罗曼努斯四世·狄奥吉尼斯（希腊语：Ρωμανός Δ΄ Διογένης，Rōmanos IV Diogenēs；约1030年－1072年）拜占庭帝国皇帝（1068～1071年在位），原为卡帕多西亚的军事贵族，1068年迎娶君士坦丁十世的遗孀尤多西亚·马克林伯利提萨，被加冕为共治皇帝。在位期间多次领导对塞尔柱突厥人的军事行动。1071年，罗曼努斯四世在曼齐刻尔特战役中战败，被塞尔柱突厥人俘虏。罗曼努斯被释放时，君士坦丁十世的长子已被拥立为唯一皇帝，即米海尔七世。罗曼努斯被刺瞎双目，流放到马尔马拉海的普罗蒂岛（今土耳其克纳勒岛），直至去世。

Romanos IV Diogenes (Greek: Ρωμανός Δʹ Διογένης, Rōmanós IV Diogénēs), also known as Romanus IV, was a member of the Byzantine military aristocracy who, after his marriage to the widowed empress Eudokia Makrembolitissa, was crowned Byzantine emperor and reigned from 1068 to 1071. During his reign he was determined to halt the decline of the Byzantine military and to stop Turkish incursions into the Byzantine Empire, but in 1071 he was captured and his army routed at the Battle of Manzikert. While still captive he was overthrown in a palace coup, and when released he was quickly defeated and detained by members of the Doukas family. In 1072, he was blinded and sent to a monastery, where he died of his wounds.