| Karina | | kah-REE-nah (Swedish, Polish, German, Russian), kə-REE-nə (English) | Swedish, Danish, Norwegian, Polish, German, Russian, English | |
| Karp | | KAHRP | Russian | |
| Katenka | | - | Russian | |
| Katerina | | - | Macedonian, Russian, Bulgarian, Greek, Late Roman | |
| Katia | | KAH-tyah | Russian | |
| Katya | | KAH-tyah | Russian | |
| Kazimir | | kah-zee-MEER (Russian) | Russian, Medieval Slavic | |
| Kesha | | - | Russian | |
| Khariton | | - | Russian | |
| Kir | | KEER | Russian | |
| Kira (1) | | KEE-rah | Russian | |
| Kirill | | kee-REEL | Russian | |
| 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 | |