Edmund the Martyr (also known as St Edmund or Edmund of East Anglia, died 20 November 869) was king of East Anglia from about 855 until his death.
Few historical facts about Edmund are known, as the kingdom of East Anglia was devastated by the Vikings, who destroyed any contemporary evidence of his reign. Coins minted by Edmund indicate that he succeeded Æthelweard of East Anglia, as they shared the same moneyers. He is thought to have been of East Anglian origin, but 12th century writers produced fictitious accounts of his family, succession and his rule as king. Edmund's death was mentioned in the Anglo-Saxon Chronicle, which relates that he was killed in 869 after the Great Heathen Army advanced into East Anglia. Medieval versions of Edmund's life and martyrdom differ as to whether he died in battle fighting the Great Heathen Army, or if he met his death after being captured and then refusing the Viking leaders' demand that he renounce Christ.
A popular cult emerged after Edmund's death, and he was canonised by the Church. A series of coins commemorating him was minted from around the time East Anglia was absorbed by the kingdom of Wessex in 918, and in about 986, the French monk Abbo wrote of his life and martyrdom.
During the 10th century, Edmund's remains were translated from an unidentified location in East Anglia to Beodricesworth (modern Bury St Edmunds); they were temporarily moved to London for safekeeping in 1010. Edmund's cult flourished during the Early and High Middle Ages, and he and Edward the Confessor were regarded as the patron saints of medieval England until they were replaced by Saint George in the 15th century. Medieval manuscripts and works of art relating to Edmund include Abbo's Passio Sancti Eadmundi, John Lydgate's 15th-century Life, the Wilton Diptych, and a number of church wall paintings.
The existence of Edmund is known from coins minted by his moneyers, three of whom—Dudda, Eadmund, and Twicga—minted coins for Edmund's predecessor, Æthelweard which suggests that a smooth transition of power occurred.