Ethelbert (or Æthelbert, or Aethelberht) (c. 552 - February 24, 616) was a King of Kent from around 580 or 590 to 616. After his death, he was regarded as a saint.

He was the son of Eormenric , whom he succeeded as king, according to the Anglo-Saxon Chronicle. Gregory of Tours, who was a close acquaintance of Queen Ingoberg (the mother of Ethelbert's wife Berthe), twice calls him simply "a man of Kent", indicating that he was not king at the time Gregory's History of the Franks was written, and that Ethelbert more likely became king closer to 590.

The Anglo-Saxon Chronicle records that he attempted at one stage to wrest the position of Bretwalda from Ceawlin of Wessex but was unsuccessful. His standing was advanced by his marriage with Berthe, daughter of Charibert, king of the Franks, thus building an alliance with the most powerful state in Europe at that time. This prestige enabled him to claim the title of Bretwalda after Ceawlin's death.

The influence of Berthe, who had brought her chaplain Liuhard (or Letard) with her to Kent, may have led to the invitation to Pope Gregory I to send missionaries from Rome. Augustine landed on the Isle of Thanet in 597, and Ethelbert first met him under an oak tree, in accordance with his belief that he could thus dispel any magic the Christians might attempt. Tradition has it that Augustine baptized Ethelbert only a few days after landing in Kent, although a letter from Gregory to Berthe suggests that it cannot have happened before 601. In any case, churches were established and efforts began to convert the people to Christianity.

Ethelbert also established a written code of laws for Kent, the earliest in any Anglo-Saxon kingdom, which provided for the protection of the Church and instituted a complex system of fines.

Ethelbert was later canonised for his role in restoring Christianity to England. Although he died on February 24, 616, his feast day was usually celebrated on February 25 so that it would not overlap with the feast of Saint Matthias on the previous day.