Saint Ansgar, Anskar or Oscar, (September 8, 801 – February 3, 865, in Bremen) was an Archbishop of Hamburg-Bremen. The see of Hamburg was designated a "Mission to bring Christianity to the North", and Ansgar became known as the "Apostle of the North".

After his mother’s early death, Ansgar was brought up in Corbie Abbey, and made rapid progress in his education. According to the Vita Ansgarii ("Life of Ansgar"), when the little boy learned in a vision that his mother was in the company of Saint Mary, his careless attitude toward spiritual matters changed to seriousness ("Life of Ansgar", 1). His pupil, successor, and eventual biographer Rimbert considered the visions of which this was the first to be the main motivation of the saint's life.

Ansgar was a product of the phase of Christianization of Saxony (present day Northern Germany) begun by Charlemagne and continued by his son and successor, Louis the Pious. When Saxony was no longer the focus of Christianization, what is now Denmark fell under the sweeping missionary gaze, with a group of monks including Ansgar sent back to Jutland with the baptized Jutish king Harald Klak. Ansgar returned two years later after educating young boys who had been purchased because Harald had possibly been driven out of his kingdom. In 822 Ansgar was one of a number of missionaries sent to found the abbey of Corvey (New Corbie) in Westphalia, and there became a teacher and preacher. Then in 829 in response to a request from the Swedish king Björn at Hauge for a mission to the Swedes, Louis appointed Ansgar missionary. With an assistant, the friar Witmar, he preached and made converts for six months at Birka, on Lake Mälaren. They organized a small congregation there with the king's steward, Hergeir, as its most prominent member. In 831 he returned to Louis' court at Worms and was appointed to the Archbishopric of Hamburg.