Flaithbertach Ua Néill (before 978–1036) was king of Ailech, a kingdom of north-west Ireland. He abdicated in 1030 and undertook a pilgrimage to Rome, for which reason he was known as Flaithbertach an Trostáin (Flaithbertach of the Pilgrim's staff). Following the death of his son Áed in 1033, Flaithbertach left his retirement and resumed the leadership of the Northern Uí Néill.