Harald Klak was the Viking leader traditionally identified as the first Scandinavian king to be baptised.
Harald Klak was a Danish ruler who sought support from the Frankish emperor Louis the Pious during ninth-century struggles for power in Denmark. As part of this relationship, Harald was baptised at Ingelheim in 826, with members of his household also receiving baptism.
The missionary Ansgar accompanied Harald when he returned north, and the mission helped establish an early Christian presence in Denmark. Harald’s baptism did not immediately convert Scandinavia: Christianity spread unevenly, and pagan religious practices remained influential for generations.
Harald Klak is often confused with Harald Bluetooth, the later Danish king who promoted Christianity and ruled in the tenth century. Harald Bluetooth’s conversion and royal patronage were much more politically significant, but he was not the same person and lived roughly a century later.