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. Edmund's death was mentioned in the Anglo-Saxon Chronicle, which relates that he was killed in 869 after being captured and then refusing the Viking leaders' demand that he renounce Christ.

After Edmund refusal to renounce Christ he was subsequently tied to a tree and killed with bow and arrow. In about 986, the French monk Abbo wrote of his life and martyrdom.

During the 10th century, Edmund's remains were moved from an unidentified location in East Anglia to Beodricesworth (modern Bury St Edmunds.

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.