| Name | Meaning | Gender | Origin |
|---|
| Jaffa | beautiful | Female | Hebrew |
| Jamal | beauty | Male | Arabic |
| Jasmine | Flower
| Female | Persian |
| Jasper | Black stone
| Male | Persian |
| Jasper | Black stone
| Male | Persian |
| Jasper | Black stone
| Male | Persian |
| Java | Brewed coffee | Female | Anglicization |
| Jay | jaybird | Male | Latin |
| Jen | White, Fair | Unisex | English |
| Jennie | English, God's gracious gift | Female | English |
| Jennifer | white shadow, white wave | Female | Cornish |
| Jenny | Diminutive of Jane and Jennifer.
| Female | English |
| Jenny | Diminutive of Jane and Jennifer.
| Female | English |
| Jester | A fool at medieval courts | Unisex | |
| Jet | A deep black colour. Aircraft engine that propels an aircraft forward by expelling exhaust gases toward the rear. | Male | Mineral |
| Jett | Jet Black Gem | Male | English |
| Jetta | jet | Female | English |
| Jonquil | Reed | Female | English |
| Juniper | Juniper Tree | Female | English |
| Kala | time, black | Unisex | |
| Kali | after the Indian goddess of death | Female | Sanskrit |
| Kalli | Energy, Black Goddess | Unisex | Hindu |
| Kane | tribute, warrior; the doubly-accomplished, golden; man, the eastern sky; beautiful | Male | Celtic |
| Kara | pure | Female | English |
| Keira | after the actress Keira Knightley | Female | Irish |