Ess Ruaid: Assaroe; a cataract on the River Erne near Ballyshannon, in the south of the County Donegal. It constituted part of the old boundary between Ulster and Connacht
Etarbane: one of the "seats" of the king of Cashel, in Tipperary
Ethliu: father of Lug
Ethne: sister of Medb (pronounced Ehnna)
Fachtna Fathach: king of Ulster and later of all Ireland; adoptive father of Conchobar and husband of Ness, Conchobar's mother
Fal (or Inisfail): one of the bardic names for Ireland; Medb is called "of Fal," as daughter of the High King of Ireland (pronounced Fawl)
Fan na Coba: a territory in the baronies of Upper and Lower Iveagh, in the County Down
Fedain Cualngi: a place in Ulster
Fedlimid Nocruthach: daughter of King Conchobar, wife of Loegaire Buadach, mother of Fiachna and cousin-german of Cuchulain (pronounced Falemid)