Eowils and Halfdan (Healfdan) were kings in Danish (Viking) ruled Northumbria in the early tenth century.
Æthelwold was unable to get significant support in Wessex and fled to Northumbria, where he was accepted as king, but he was killed by Edward's men at the Battle of the Holme in 902.
In the following years there seems to have been no clear leadership in Northumbria as no kings are named on coins of the period.
The Anglo-Saxon Chronicle names two kings among the Danish dead called Eowils and Halfdan.
In Æthelweard's Chronicon, a Latin translation of the Anglo-Saxon Chronicle, a third king, Ingwær, is also named as killed at Tettenhall.