Cian, son of Diancecht, [62], [63], [78], [84], [90]-94, [106], [235]-237, [239], [269], [345], [371].

Ciaran, Saint, [10].

Cichol the Footless, a Fomor, [66].

Cilgwri, the Ousel of, [349].

Clann Baoisgne, [209], [217], [222]:

Clan Chattan, [415].

Clann Morna, [209], [211], [218], [232].

Clann Neamhuinn, [216], [218].

Clann Ronan, [218].

Clas Myrddin, an old name for Britain, [323].