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].