Æthelhere (died 15 November 655) was King of East Anglia from 653 or 654 until his death. He was a member of the ruling Wuffingas dynasty and one of three sons of Eni to rule East Anglia as Christian kings. He was a nephew of Rædwald, who was the first of the Wuffingas of which more than a name is known.
Rædwald and his son Eorpwald both ruled as pagans before being converted to Christianity. After Eorpwald's murder in around 627, the East Angles briefly reverted to heathenism, before Christianity was re-established by Sigeberht. Sigeberht eventually abdicated in favour of his co-ruler Ecgric, after which the East Angles were defeated in battle by the Mercians, led by their king Penda, during which both Ecgric and Sigeberht were slain. The monks at Cnobheresburg were driven out by Penda in 651 and Ecgric's successor Anna was forced into temporarily exile. In 653 Penda once again attacked East Anglia and at the Battle of Bulcamp, Anna and his son were slain and the East Anglian army was defeated. Æthelhere then became king of the East Angles, possibly ruling jointly with his surviving brother, Æthelwold. During Æthelhere's brief reign, it is known that Botolph's monastery at Iken was built.
In 655, Æthelhere was one of thirty noble warlords who joined with Penda in an invasion of Northumbria, laying siege to Oswiu and the much smaller Northumbrian army. The battle was fought on 15 November 655, near the Winwæd, an unidentified river. The Northumbrians were victorious and many of the Mercians and their allies were killed or drowned. In the battle, Penda and nearly all his warlords, including Æthelhere, were killed.