Flemish priest famed in his day for his learning and writings.

Alger was first a deacon of the Church of Saint-Barthélemy at Liège and was appointed (c. 1100) to the cathedral church of St. Lambert. He declined many offers of posts from German bishops and retired to the Monastery of Cluny.

His History of the Church of Liège and many of his other works are lost. The most important of those remaining are Liber de misericordia et justitia (“On Mercy and Justice”), a collection of biblical and patristic extracts with a commentary—an important work for the history of church law and discipline; De sacramentis corporis et sanguinis Dominici (“Concerning the Sacraments of the Body and the Blood of the Lord”), a treatise on the Eucharist in opposition to the Berengarian heresy and highly commended by Peter of Cluny and Erasmus; Libellus de libero arbitrio (“On Free Will”), in B. Pez's Anecdota (vol. 4); and De sacrificio missae (“On the Sacrifice of the Mass”), in the Scriptorum veterum nova collectio (“New Collection of Ancient Writers”) of Angelo Mai (vol. 9).