Fiachra is an Irish male given name. It may refer to:
Clerics
- Saint Fiacre of Breuil (died 670), missionary in France
- Fiachra mac Colmain (500-558) Bishop of Armagh
- Fiachra Ua Focarta (died 1006) abbot of Clonfert
- Fiachra Ó Ceallaigh (born 1933) bishop of Dublin
Legendary kings
- Fiachrae son of Eochaid Mugmedon and namesake of Tireragh, County Sligo
- Fiachra Suighe legendary pre-Christian founder of the Dal Fiachrach Suighe
- Fiacha mac Delbaíth, legendary High King
Medieval kings
- Fiachra Cossalach (died 710) king in Ulster
- Fiachra Finn (fl 5th century) king of Uí Maine in Connacht
Sportsmen
- Fiachra McArdle (b.1983) association footballer
- Fiachra Breathnach (b.1986) Gaelic footballer from Galway
- Fiachra Lynch (b.1987) Gaelic footballer from Cork
Other
- Fiachra, mythological son of Ler from the Children of Lir legend
- Fiachra Mac Brádaigh (1690-1760) writer
- Fiachra Trench (b.1941) composer