| Katja | | KAHT-yah (German, Dutch) | German, Swedish, Norwegian, Danish, Dutch, Slovene | |
| Katrin | | kah-TREEN (German, Swedish) | German, Swedish, Estonian | |
| Katrina | | kə-TREE-nə (English), kaht-REE-nah (Dutch) | English, German, Swedish, Dutch | |
| Kay (3) | | KIE (Swedish) | Frisian, German, Swedish, Norwegian, Danish | |
| Kayetan | | KAH-ye-tahn | German | |
| Kerstin | | SHESH-tin (Swedish), KER-stin (German) | Swedish, German | |
| Kevin | | KEV-in (English) | English, Irish, French, German, Dutch, Swedish, Norwegian, Danish | |
| Kiki | | KEE-kee (English), kee-KEE (Greek) | English, German, Greek | |
| Kilian | | KEE-lee-ahn (German) | German, Irish, French | |
| Kinge | | KING-ə | German | |
| Klaas | | KLAH:S | Dutch, Low German | |
| Klara | | KLAH-rah (German, Russian, Polish) | Swedish, Norwegian, Danish, Icelandic, German, Russian, Ukrainian, Polish, Slovene, Croatian | |
| Klaus | | KLOWS (German, Finnish) | German, Danish, Norwegian, Finnish | |
| Klemens | | KLE-mens (German, Polish) | German, Danish, Swedish, Polish | |
| Knut | | KNOOT (German) | Swedish, Norwegian, Danish, German | |