阿莱克修斯一世·科穆宁（希腊语：Αλέξιος Α' Κομνηνός，1048年－1118年8月15日）科穆宁王朝的东罗马帝国皇帝（1081年－1118年在位）。他在拜占庭率兵废黜尼基弗鲁斯三世而恢复了科穆宁家族由于伊萨克一世被废黜而中断的统治。

阿莱克修斯一世在东罗马帝国四面受敌的形势下继承皇位。在西方，诺曼人企图蚕食帝国的欧洲领土；在东方则有更可怕的敌人塞尔柱帝国正在虎视耽耽。阿莱克修斯一世在即位后第一年与威尼斯共和国结盟，以抵御由罗贝尔·吉斯卡尔率领的诺曼人对希腊的侵袭。他最终于1085年打败了罗贝尔·吉斯卡尔。为换取与威尼斯的盟约，他给予威尼斯商人在东方贸易中的许多特权。1091年，阿莱克修斯一世借波洛韦茨人之力打败了入侵帝国的佩切涅格人。在同年，通过与塞尔柱帝国者签订条约，阿莱克修斯一世使东方的局势暂时稳定下来。1093年他废黜了在安纳托利亚的埃米尔查哈。

Alexios I Komnenos (Greek: Ἀλέξιος Αʹ Κομνηνός, 1048 or 1056 – 15 August 1118), Latinized as Alexius I Comnenus, was Byzantine emperor from 1081 to 1118. Although he was not the founder of the Komnenian dynasty, it was during his reign that the Komnenos family came to full power. Inheriting a collapsing empire and faced with constant warfare during his reign against both the Seljuq Turks in Asia Minor and the Normans in the western Balkans, Alexios was able to halt the Byzantine decline and begin the military, financial, and territorial recovery known as the Komnenian restoration. The basis for this recovery were various reforms initiated by Alexios. His appeals to Western Europe for help against the Turks were also the catalyst that likely contributed to the convoking of the Crusades.