| Klara | | KLAH-rah (German, Russian, Polish) | Swedish, Norwegian, Danish, Icelandic, German, Russian, Ukrainian, Polish, Slovene, Croatian | |
| Klava | | - | Russian | |
| Klavdiya | | KLAHV-dee-yah (Russian) | Russian, Ukrainian, Bulgarian | |
| Klim | | - | Russian, Ukrainian | |
| Kliment | | klee-MYENT (Russian) | Russian, Ukrainian, Bulgarian, Macedonian | |
| Kobe (2) | | - | Various | |
| Kohinoor | | - | Various | |
| Kolya | | - | Russian | |
| Konstantin | | KAWN-stahn-teen (German), kahn-stahn-TEEN (Russian) | German, Hungarian, Russian, Serbian, Bulgarian, Macedonian | |
| Kostya | | - | Russian | |
| Kristina | | kris-TEE-nah (German) | Swedish, Norwegian, Danish, Russian, German, Slovene, Czech, Lithuanian, Serbian, Croatian, Faroese, | |
| Kseniya | | KSYE-nee-yah | Russian | |
| Kuzma | | kooz-MAH | Russian | |