Alexios I Komnenos (Greek: Ἀλέξιος Αʹ Κομνηνός), 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 curb 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.
Alexios was the son of the Domestic of the Schools John Komnenos and Anna Dalassena, and the nephew of Isaac I Komnenos (emperor 1057–1059). Alexios' father declined the throne on the abdication of Isaac, who was thus succeeded by four emperors of other families between 1059 and 1081. Under one of these emperors, Romanos IV Diogenes (1067–1071), Alexios served with distinction against the Seljuq Turks. Under Michael VII Doukas Parapinakes (1071–1078) and Nikephoros III Botaneiates (1078–1081), he was also employed, along with his elder brother Isaac, against rebels in Asia Minor, Thrace, and in Epirus.
Alexios' last years were also troubled by anxieties over the succession. Although he had crowned his son John II Komnenos co-emperor at the age of five in 1092, his wife, Irene Doukaina wished to alter the succession in favor of their daughter Anna and Anna's husband, Nikephoros Bryennios the Younger. Bryennios had been made kaisar (Caesar) and received the newly created title of panhypersebastos ("honoured above all"), and remained loyal to both Alexios and John. Nevertheless, the intrigues of Irene and Anna disturbed even Alexios' dying hours.