| Katarina | | kah-tah-REE-nah (German, Swedish) | German, Swedish, Norwegian, Danish, Hungarian, Croatian, Serbian, Slovene | |
| Konstantin | | KAWN-stahn-teen (German), kahn-stahn-TEEN (Russian) | German, Hungarian, Russian, Serbian, Bulgarian, Macedonian | |
| Kornelija | | - | Croatian, Serbian | |
| Kristijan | | KREES-tee-yahn (Serbian, Croatian) | Serbian, Croatian, Slovene, Macedonian | |
| Kristina | | kris-TEE-nah (German) | Swedish, Norwegian, Danish, Russian, German, Slovene, Czech, Lithuanian, Serbian, Croatian, Faroese, | |
| Ksenija | | - | Serbian, Croatian, Macedonian, Slovene | |
| Kuzman | | - | Bulgarian, Serbian, Macedonian | |