He was the count (Graf) of Dießen-Andechs, leading the Bavarians against invading Magyars in the tenth century.

No contemporary Vita of Rasso has survived and various legends arose around his cult in the late Middle Ages.

[3] As a middle-aged man, he went on a pilgrimage to the Holy Land and Rome, where he collected relics, returning to found a Benedictine abbey at Wörth, later named Grafrath after him.

[1] The healing shrine and pilgrimage church (Wallfahrtskirche) of St. Rasso at Grafrath received many visitors during the Middle Ages and afterwards; records of the miracles attributed to him between the years 1444 and 1728 consist of 12,131 entries.

[1] In 955, the relics that Rasso had brought from Rome and the Holy Land to his monastery at Wörth were transferred to Andechs Abbey to preserve them from the ravages of the Magyars.