Faílbe Flann mac Áedo Duib (died 639) was a King of Munster from the Eóganacht Chaisil branch of the Eoganachta. He succeeded Cathal mac Áedo Flaind Chathrach of the Glendamnach branch in 628. He was the younger brother of a previous king Fíngen mac Áedo Duib (d. 618). His sobriquet Flann meant "blood-red".