Cináed mac Conaing (died 851) was King of Knowth in the medieval Irish province of Mide, succeeding his father Conaing mac Flainn in 849. Cináed's family belonged to the Knowth, or Uí Chonaing, branch of the Síl nÁedo Sláine, part of the southern branch of the dominant Uí Néill kin group. The leadership of the southern branch rested with the rival Clann Cholmáin whose chief, Máel Sechnaill mac Máele Ruanaid, was High King of Ireland. Even within the Síl nÁedo Sláine, Cináed and his kin had a rival in the shape of Tigernach mac Fócartai, king of Lagore.