Gall according to hagiographic tradition was a disciple and one of the traditional twelve companions of Columbanus on his mission from Ireland to the continent. However, he may have originally come from the border region between Lorraine and Alemannia and only met Columbanus at the monastery of Luxeuil in the Vosges. Gall is known as a representative of the Irish monastic tradition. The Abbey of Saint Gall in the city of Saint Gallen, Switzerland was built upon his original hermitage. Deicolus was the elder brother of Gall.

Columbanus was an Irish missionary notable for founding a number of monasteries after 590 in the Frankish and Lombard kingdoms, most notably Luxeuil Abbey in present-day France and Bobbio Abbey in present-day Italy.