Rodulfus (or Ralph) Glaber (which means "the Smooth" or "the Bald") (985–1047) was an 11th-century French monk and chronicler.
Glaber was born in 985 in Burgundy, France. At the behest of his uncle, a monk at Saint-Léger-de-Champeaux, Glaber was sent to a monastery at the age of twelve, but he was eventually expelled for disobedience. Later he spent time in various other monasteries, such as Moutiers-Saint-Jean, Saint-Bénigne à Dijon, and Saint-Germain d'Auxerre.
Around the year 1010, he joined the monastery of St. Benignus near Dijon where he met a reform-minded cleric from Piedmont, William of Volpiano, Abbot of Saint-Bénigne. In 1028 he traveled to Italy with Volpiano, who encouraged him to write what would become his masterpiece, the Historiarum libri quinque ab anno incarnationis DCCCC usque ad annum MXLIV ("History in five books from 900 AD to 1044 AD"). The chronicle was dedicated to the Abbot of Cluny, Odilo. Today a few manuscripts of the Historiarum survive, including the author's original copy. As a second work, Rodulfus wrote a biography of Volpiano, which probably arose shortly after his death in 1031. That year, he moved to the Abbey of Cluny, which was headed by Abbot Odilon de Mercœur. In 1039 he joined the Abbey of Saint-Germain en Auxerre, where he remained until his death.
Glaber is credited with coining the phrase "white mantle of churches", describing the ubiquity of religious architecture of the times.