He was a son of Niall of the Nine Hostages, and one of the progenitors of the Southern Uí Néill dynasties.
[2] Conall son of Niall was nicknamed Cremthainne (possibly denoting fosterage among the Uí Chremthainn of Airgialla), to distinguish him from his brother Conall Gulban, ancestor of the Cenél Conaill.
The habit of giving the same name to different sons remained common among the prolific Irish princes until the sixteenth century.
[5] Through his son Fergus Cerrbél, he was the ancestor of the Clann Cholmáin and Síl nÁedo Sláine.
Another son was Ardgal mac Conaill (died 520), ancestor of the Cenél nArdgail in County Meath.