Alger (Algerus canonicus Leodiensis) lived between the second half of the eleventh century and the first half of the twelfth century, in the age of the Investiture Controversy. His biography is mainly known through the Elogium written during his lifetime by the canon Nicholas of Liège, as an introduction to his ‘redaction’ of Alger’s two treaties. Neither the date nor place of his birth are known and the nickname ‘of Liège’ is more a reference to the city where he made his career as a member of the secular clergy, before entering the monastery of Cluny at a later stage in his life.