Ceolnoth or Ceolnoþ (; died 870) was a medieval English Archbishop of Canterbury. Although later chroniclers stated he had previously held ecclesiastical office in Canterbury, there is no contemporary evidence of this, and his first appearance in history is when he became archbishop in 833. Ceolnoth faced two problems as archbishop – raids and invasions by the Vikings and a new political situation resulting from a change in overlordship from one kingdom to another during the early part of his archiepiscopate. Ceolnoth attempted to solve both problems by coming to an agreement with his new overlords for protection in 838. Ceolnoth's later years in office were marked by more Viking raids and a decline in monastic life in his archbishopric.
Archbishop
Gervase of Canterbury wrote at the end of the twelfth century that Ceolnoth was Dean of the see of Canterbury previous to being elected to the archiepiscopal see of Canterbury, but this story has no confirmation in contemporary records. There is no sign of him being associated with either Canterbury or Kent, the region where Canterbury is located, prior to his elevation as archbishop. Given the length of his archiepiscopate, he was probably a young man when he was elected to Canterbury. Upon becoming archbishop, Ceolnoth had to deal with two problems – first the Viking attacks on his archbishopric and the surrounding lands in Kent and second the newly ascendant kings of Wessex who had just gained control of Kent. Previously, the Mercian kings had ruled Kent. This was the last time that the archbishop worked in concert with a Mercian king, as, after this, he was an attendee at the Wessex royal court instead of the Mercian. This agreement gave control of all of the free minsters under Canterbury's authority to the king in return for protection from Viking raids. Ceolnoth also ceded the right to influence the election of abbots within Kent to the king. Ceolnoth also recovered control of some lands that had been lost by Canterbury. During his later years in office, he was assisted by four clerics, who appear to have been or acted as archdeacons, one of the earliest appearances of this office in England. Ceolnoth is also known to have corresponded with Pope Leo IV.
Ceolnoth died on 4 February 870.