| Jordanes | | - | Ancient Germanic | |
| Jovian | | - | Ancient Roman (Anglicized) | |
| Judda | | - | Ancient Germanic | |
| Judoc | | - | Breton, Ancient Celtic | |
| Judocus | | - | Dutch (Archaic), Ancient Celtic (Latinized) | |
| Juliana | | yuy-lee-AH-nah (Dutch), yoo-lee-AH-nah (German), joo-lee-AHN-ə (English) | Dutch, German, English, Spanish, Portuguese, Ancient Roman | |
| Julius | | YOO:-li-uws (Ancient Roman), JOO-lee-əs (English), YOO-lee-uws (German) | Ancient Roman, English, German | |
| Junia | | - | Biblical, Ancient Roman | |
| Junius | | - | Ancient Roman | |
| KÁRi | | - | Ancient Scandinavian | |
| KÓRi | | - | Ancient Scandinavian | |
| Kallias | | - | Ancient Greek | |
| Kallikrates | | - | Ancient Greek | |
| Kallisto | | - | Greek Mythology, Ancient Greek | |
| Kallistos | | - | Ancient Greek | |