| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Jonas (1) | YO-nus | Lithuanian | ||
| Judita | - | Lithuanian, Czech, Slovak | ||
| Julija | YOO-lee-yah (Slovene) | Slovene, Croatian, Lithuanian | ||
| Juozapas | - | Lithuanian | ||
| Juozas | - | Lithuanian | ||
| Jurgis | - | Lithuanian | ||
| Justina | jus-TEE-nə (English) | English, Slovene, Czech, Lithuanian, Late Roman | ||
| Justinas | - | Lithuanian | ||
| KĘStutis | - | Lithuanian | ||
| Kajus | - | Lithuanian | ||
| KamilĖ | - | Lithuanian | ||
| Karolina | kah-raw-LEE-nah (Polish), kah-ro-LEE-nah (Swedish, German) | Polish, Swedish, Norwegian, Danish, Hungarian, Slovene, Croatian, Macedonian, Lithuanian, German | ||
| Karolis | - | Lithuanian | ||
| Kasparas | - | Lithuanian | ||
| KatrĖ | - | Lithuanian |