Or in the English Elmet from the Latin Elmetia; a Romano-British kingdom of uncertain extent but based in what is now known as west Yorkshire and centered on Loidis (modern Leeds). From about the late 5th century it formed a bridgehead separating the Anglo-Saxon kingdoms of Deira and Bernicia to the north and east, from that of Mercia in the south until 617 AD when Elfed was absorbed within the expanding kingdom of Northumbria as part of its push westwards towards the Pennines.

Little is known about the history of Elfed other than the last king was known as Ceredig and that in around 617 AD he was driven out the kingdom by Edwin of Northumbria. Although it is very likely that Elfed was already tributary to Northumbria before, as Aethelfrith appeared to have no trouble in moving his forces across the country in 615 AD for the battle of Chester.

Ceredig was probably the son of Gwallog who was king in the late 6th century and features in the poetry of Taliesin as a "skilled warrior" who "inspired terror from Dunbarton to the borders of mid-Wales".

The name Elmet survives in a number of placenames within the west Yorkshire region, specifically Sherborne-in-Elmet which is a suburb of modern Leeds. There is also an early Christian memorial stone, probably from the late fifth or early sixth century, at Llanaelhaearn church in north Wales that reads, ALIORTUS ELMETIACO HIC IACET or Here lies Aliortus from Elmet