| Name | Meaning | Gender | Origin |
|---|
| Ian | Form of John | Male | Scottish |
| Ignacio | fiery | Male | Spanish |
| Igor | Scottish variation of Welsh Ifor, lord or English form of Scandinavian Ifar, yew | Male | Russian |
| Isaac | laughing one | Male | Hebrew |
| Isaiah | salvation of the Lord | Male | Hebrew |
| Ivan | Form of John | Male | Russian |
| Ivor | yew | Male | Scottish |
| Jack | after the Georgetown University mascot, Jack the Bulldog | Male | English |
| Jack | From John - God's gracious gift | Male | English |
| Jackson | Son of Jack | Male | English |
| Jacques | supplanter | Male | |
| James | From Jacob - To fill the place of another, supplanter. | Male | English |
| Jaromir | Spring, Favor | Unisex | Czechoslovakian |
| Jason | the Lord is salvation | Male | Hebrew |
| Javier | Born in January
| Male | Spanish |
| Jax | God has been gracious: has shown favor. Based on John or Jacques.
| Male | Modern |
| Jay | jaybird | Male | Latin |
| Jean | God is gracious | Male | |
| Jean-Claude | | Unisex | Hebrew |
| Jeff | pledge of peace | Male | English |
| Jeffrey | pledge of peace | Male | Spelling |
| Jeremy | God will uplift, appointed by God | Male | English |
| Jerome | sacred name | Male | Greek |
| Jerry | after Jerry Garcia, The Grateful Dead | Male | English |
| Jerzy | farmer | Male | Polish |