names origin: celtic
| Name | Meaning | |
| Carrol, carroll | Champion... | More... |
| Cary, carey | The dark one... | More... |
| Casey | Brave... | More... |
| Cassivellaunus, caswallan | Arthurian myth name... | More... |
| Cathal, cahal, conall, co | Strong in battle... | More... |
| Cathbad | Meaning unknown... | More... |
| Cedric | Chief... | More... |
| Celyddon | Myth name (father of Culhwch)... | More... |
| Chad | Defense... | More... |
| Cinnia, cinnie | Beauty... | More... |
| Clust | Myth name (son of Clustfeinad)... | More... |
| Clustfeinad | Myth name... | More... |
| Cocidius | Myth name (a hunter god)... | More... |
| Coinneach | Handsome... | More... |
| Conall | Myth name (Ulster chieftain)... | More... |
| Conall cernach | Myth name (Ulster chief)... | More... |
| Conan, conant, con, conn, | Wise... | More... |
| Conchobar | Myth name (a hero)... | More... |
| Condan, condon | Dark-haired wise man... | More... |
| Conlaoch | Meaning unknown... | More... |
| Conn | Myth name (son of Lir)... | More... |
| Connla | Myth name (son of Conn)... | More... |
| Conroy | Persistent... | More... |
| Conway | Hound of the plain... | More... |
| Corann | Myth name (a druid)... | More... |
| Cordelia | Of the sea... | More... |
| Cormac, cairbre, carbry | Charioteer... | More... |
| Coventina | Water goddess... | More... |
| Cradawg | Myth name (son of Bran)... | More... |
| Cuchulain | Myth name (the Hound of Ulster)... | More... |
| Culain, culann | Myth name (the smith)... | More... |
| Culhwch | Meaning unknown... | More... |
| Cullen | Cub... | More... |
| Custennin | Myth name (a giant)... | More... |
| Cynyr | Meaning unknown... | More... |
| Daghda | Meaning unknown... | More... |
| Dallas | Dwells by the waterfall... | More... |
| Daman | Demon... | More... |
| Dana | From Denmark... | More... |
| Darcy | Dark... | More... |
| Dearg | Son of Daghda... | More... |
| Dechtire | Myth name (a nursemaid)... | More... |
| Deirdre | Sorrowful... | More... |
| Deoch | Myth name (a princess of Munster)... | More... |
| Dermot | Free... | More... |
| Desmond | From south Munster... | More... |
| Devin, devyn | Poet... | More... |
| Dillion | Faithful... | More... |
| Dinsmore | From the hill fort... | More... |
| Diva, deva, devona, divon | Divine one... | More... |
| Doane | From the sand hill... | More... |
| Donald, don, doyle, doy, | Dark stranger... | More... |
| Donat, donal, domhnall, d | Stranger... | More... |
| Donella | Dark-haired elfin girl... | More... |
| Donia | Dark-skinned... | More... |
| Donnally, donnelly | Brave, dark man... | More... |
| Donnchadh, donogh, donagh | Strong fighter... | More... |
| Doreen, doreena | Moody... | More... |
| Doughlas, douglas | Dwells by the dark stream... | More... |
| Drem | Myth name (son of Dremidydd)... | More... |
| Driscoll, driscol, driske | Interpreter... | More... |
| Druce | Wise... | More... |
| Drudwyn | Myth name (Mabon's dog)... | More... |
| Drummond | Lives on the hill top... | More... |
| Duane, dewain, dwayne | Song... | More... |
| Duer | Hero... | More... |
| Duff, dubv, duffy | Dark-faced... | More... |
| Duncan, dunham | Dark-skinned fighter... | More... |
| Dyfed | From Dyfred... | More... |
| Ea, edan | Fire... | More... |
| Eburacon | Lives near the yew-tree estate... | More... |
| Edana, ena | Passionate... | More... |
| Edna, ena, ethne | Fire... | More... |
| Efnisien | Myth name (son of Euroswydd)... | More... |
| Egan, eghan | Ardent... | More... |
| Egomas | Meaning unknown... | More... |
| Einion | Anvil... | More... |
| Elidor | Myth name (a monk)... | More... |
| Emrys | Celtic form of Ambrose (immortal)... | More... |
| Enid | Geist (spirit)... | More... |