Final answer:
Augustine of Canterbury was the man responsible for converting King Ethelbert of Kent to Christianity, a pivotal event in the Christianization of Anglo-Saxon England.
Step-by-step explanation:
The man who converted the king in Kent was Augustine of Canterbury. Augustine was a missionary who had been commissioned by Pope Gregory the Great to undertake the Christianization of the Anglo-Saxons in England. With the support of King Ethelbert's Christian wife, Bertha, Augustine successfully persuaded the king to convert to Christianity, thereby facilitating the spread of Catholic Christian beliefs throughout his realm.
This event was pivotal in consolidating the relationship between rulers and the Church, highlighting the significance of religious conversion in the establishment of political alliances and cultural transformation.