| Name | Meaning | Gender | Origin |
|---|
| Jethro | Pre-eminence | Male | Hebrew |
| Jewel | Precious stone | Female | English |
| Jinx | Magic charm | Female | Latin |
| Jupiter | Father god | Unisex | Latin |
| Justice | Righteous | Unisex | Latin |
| Kelly | War | Female | Gaelic |
| Killer | | Unisex | Hebrew |
| King | King's forest clearing | Male | English |
| Klingon | | Unisex | Hebrew |
| Koda | The allies | Unisex | Native American |
| Kodiak | Island | Unisex | Russian |
| Kojak | | Unisex | Hebrew |
| Kong | Empty, hollow, void | Male | Chinese |
| Kujo | | Unisex | Hebrew |
| Lacy | Lacy | Female | English |
| Langston | Long stone | Male | English |
| Laramie | Surname With American Connotations Due To Laramie: A Town In Wyoming USA On The Overland Trail Of The Pony Express. | Unisex | American English |
| Lester | From Leicester | Male | English |
| Liberty | Freedom | Female | Latin |
| Licorice | Confection made from the licorice root. | Unisex | English |
| Lincoln | Lake settlement, lake colony | Male | English |
| London | From London | Male | English |
| Magnum | A large type of wine bottle. | Unisex | English |
| Magnus | Great | Male | Latin |
| Majestic | | Unisex | Hebrew |
| Mako | Child of truth | Unisex | Japanese |
| Manley | Common clearing | Male | English |
| Marble | | Unisex | Hebrew |
| Maverick | Dissenter | Unisex | English |
| Maxi | Pet form of names starting with Max | Unisex | English |