| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Isidorus | - | Late Roman | ||
| Isolda | i-ZOL-də (English), i-SOL-də (English) | Arthurian Romance | ||
| Isolde | i-ZOL-də (English), i-SOL-də (English), ee-ZAWL-du (German) | English (Rare), German, Arthurian Romance | ||
| Italus | - | Roman Mythology | ||
| Iucunda | - | Late Roman | ||
| Iulia | YOO:-li-a (Ancient Roman) | Romanian, Ancient Roman | ||
| Iulian | - | Romanian | ||
| Iuliana | - | Romanian, Ancient Roman | ||
| Iulianus | - | Ancient Roman | ||
| Iuliu | - | Romanian | ||
| Iulius | YOO:-li-uws | Ancient Roman | ||
| Iunia | - | Ancient Roman, Biblical Latin | ||
| Iunius | - | Ancient Roman | ||
| Iuno | - | Roman Mythology | ||
| Iuppiter | - | Roman Mythology |