| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Cystennin | - | Welsh | ||
| Dafydd | - | Welsh | ||
| Dai | - | Welsh | ||
| Deiniol | - | Welsh | ||
| Delwyn | - | Welsh | ||
| Delyth | - | Welsh | ||
| Deryn | - | Welsh | ||
| Dewey | - | Welsh | ||
| Dewi (1) | - | Welsh | ||
| Dewydd | - | Welsh (Archaic) | ||
| Dilwen | - | Welsh | ||
| Dilwyn | - | Welsh | ||
| Dilys | - | Welsh | ||
| Drystan | - | Welsh | ||
| Dylan | DUL-an (Welsh), DIL-ən (English) | Welsh, English, Welsh Mythology |