Cognomen Mučnjak (Mučnjak 
) , all around the world, is a rare last name. The family name Mučnjak is habitual in Southern Europe, particularly Croatia, where it is quite a rare surname.
Ana, Hrvoje, Franjo, Zvonko, Zlatko, Martina, Mirjana, Stjepan, Dominik, Tihomir, Tihomil, Nevenka, Željko, Miroslav, Branimir, Katarina, Kristina, Kristian, Krešimir, Jadranka, Tomislav, Natalija, Jelena, Nikolina, Josipa, Branko, Iva, Anja, Grga, Jura, Ivan, Marko, Sanja, Paula, Dario, Darko, Damir, Goran, Josip, Juraj, Tvrtko, Irena, Ivana, Matija, Mateja, Mislav, Barica, Branka, and Valentina