| Name | Meaning | Gender | Origin |
|---|
| Horror | | Unisex | Hebrew |
| Hulk | | Unisex | Hebrew |
| Hydra | | Unisex | Hebrew |
| Imp | | Unisex | Hebrew |
| India | Of India | Female | English |
| Isis | throne | Female | Egyptian |
| IT | | Unisex | Hebrew |
| Ivy | ivy plant, a wine | Female | Plant |
| Jack-o-Lantern | | Unisex | Hebrew |
| Jacquelyn | Feminine of Jacques derived from James and Jacob.
| Female | |
| Java | Brewed coffee | Female | Anglicization |
| Jaws | Bones that form the mouth. A dangerous situation - "The Jaws of Death" | Unisex | |
| Jekyll | | Unisex | Hebrew |
| Jetta | jet | Female | English |
| Jezebel | follower of idols | Female | Hebrew |
| Jillian | Jove's child. Variant of Gillian from the masculine Julian.
| Female | Phonetic |
| Jinx | Charm, Spell | Female | Latin |
| Jolly | Full of good humor and high spirits. | Unisex | |
| Josette | Jehovah increases | Female | |
| Jynx | Charm, Spell | Unisex | Latin |
| Kali | after the Indian goddess of death | Female | Sanskrit |
| Karen | pure | Female | Danish |
| Kat | pure | Female | English |
| Katarina | pure | Female | Czech |
| Killer | | Unisex | |