Ključ may refer to:

• Ključ, Una-Sana Canton, a town in Bosnia and Herzegovina
• Ključ, Gacko, a village in Bosnia and Herzegovina
• Ključ, Varaždin County, a village near Novi Marof, Croatia
• Ključ, Šibenik-Knin County, a village near Drniš, Croatia
• Ključ (Belgrade), a hamlet of Bečmen, Serbia
• Ključ, Mionica, a village in Serbia
• Ključ (film), a 1965 Croatian film
• Ključ Brdovečki, a village near Brdovec, Croatia
• Klyuch, the village in Bulgaria also transliterated as Ključ