| Name | Meaning | Gender | Origin |
|---|
| Crystin | Follower of Christ | Girl | |
| Culhwch | Narrow and straight | Boy | |
| Cynddelw | Exalted effigy | Boy | |
| Cynwrig | High hill | Boy | |
| Cystenian | Steadfast | Boy | |
| Dafydd | Beloved | Boy | |
| Dai | Beloved | Boy | |
| Danbrann | Heroine | Girl | |
| Deiniol | God is my Judge | Boy | |
| Delwyn | Pretty and fair, Fair, Holy, White | Unisex | |
| Delyth | Pretty | Girl | |
| Derog | Arrogant, Obstinate | Boy | |
| Deryn | Bird | Girl | |
| Dewi | Beloved | Boy | |
| Dewydd | Beloved | Boy | |
| Dillon | Great sea | Boy | |
| Dilwen | Truly blessed | Girl | |
| Dilwyn | Truly blessed | Boy | |
| Dilys | Genuine, Steadfast, True | Girl | |
| Don | Mother goddess | Girl | |
| Drystan | Forever king, Bold, Daring, Rash, Audacious | Boy | |
| Dwyn | Fair, Holy, White | Girl | |
| Dwynwen | Fair, Holy, White | Girl | |
| Dwynwyn | Fair, Holy, White | Girl | |
| Dyfed | Beloved | Boy | |
| Dyl | Great sea | Boy | |
| Dylan | Great sea | Boy | |
| Dylis | Genuine, Steadfast, True | Girl | |
| Efa | Alive, Living | Girl | |
| Eigr | Maiden, Virgin | Girl | |
| Eigyr | Maiden, Virgin | Girl | |
| Eilian | A moment in time | Unisex | |
| Eiluned | Idol, Image | Girl | |
| Eilwen | Fair, Holy, White | Girl | |
| Einion | Anvil | Boy | |
| Eira | Snow | Girl | |
| Eirian | Bright, Beautiful | Girl | |
| Eirlys | Snowflake, Snow white | Girl | |
| Eirwen | Snowflake, Snow white | Girl | |
| Elain | Fawn | Girl | |
| Elen | Torch, Moon, Moon Elope | Girl | |
| Eleri | More than full, Overflowing | Girl | |
| Elian | A moment in time | Unisex | |
| Elidyr | Brass, Bronze | Boy | |
| Elis | Lord is my god | Boy | |
| Elisud | Kind | Boy | |
|