Flaithrí mac Domnaill (died 777)[1] was a King of Connacht from the Uí Briúin branch of the Connachta.
He was the son of Domnall mac Cellaig (d.728), a previous king.
[2] The sept of Uí Briun he belonged to was the Síl Cellaig of Loch Cime.
[citation needed] In 775 the Uí Maine were defeated by the Sil Cellaig at the Battle of Achad Liac (in Cluain Acha Liag, now called Killeroran- i.e. the Uí Maine inauguration site).
[3] The annals record his death in 777, but other historians state he abdicated and died in 779.