Last name Nikolaj (Николай 
, Nikolaj 
, ניקולאי 
, and others...) , globally, is a common cognomen. The family name Nikolaj is characteristic of Kyrgyzstan, where it is a common surname, Bulgaria, where it is quite a common surname, and Armenia (explore the name in all countries). Measured by absolute frequency, it is commonest in Russia, Kyrgyzstan, and Bulgaria. Predominantly, Nikolaj is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Николай | Belarus, Ukraine, Russia, Kyrgyzstan, Kazakhstan |
| Nikolaj | Belarus, Russia, Germany, Denmark, Bulgaria |
| ניקולאי | Israel |
| نيكولاي | Yemen, Palestinian Territory, Iraq |
| 尼古拉 | China |
| ニコライ | Japan |
Mikalai, Mikalaj, Mikalay, Mikałaj, Miklavž, Miklos, Miklós, Mikola, Mikołaj, Mikuláš, Mikławš, Mykola, Mykoła, N., Niccolò, Nicholas, Nickel, Nicolaas, Nicolae, Nicolaes, Nicolai, Nicolaj, Nicolas, Nicolau, Nicolaus, Nicolay, Nicolaï, Nicolino, Nicolo, Nicolás, Nicolò, Nicos, Nicu, Niels, Nikku, Nikolai, Nikolai, Nikolaj, Nikolajs, Nikolajus, Nikolao, Nikolaos, Nikolas, Nikolass, Nikolaus, Nikolay, Nikolaz, Nikolaï, Nikolaĭ, Nikolos, Nikoloz, Nikolái, Nikos, Nikołaj, Nikulás, Nils, Nyikolaj, Νίκολας, Νίκος, Νικολάου, Νικόλαος, Νικόλας, Коля, Микалай, Миклош, Микола, Миколай, Микулаш, Мыкола, Мікалай, Міклаш, Мікола, Никель, Никколо, Никола, Николае, Николаев, Николаз, Николайс, Николаос, Николас, Николау, Николаус, Николаэ, Николо, Николоз, Николя, Никос, Нилс, Нильс, Нікалас, Нікало, Ніколай, Ніколас, Нільс, נילס, ניקולאו, ניקולס, نيقولا, نيقولاي, نيكوس, نيكولاس, نيلز, نيلس, ნიკოლასი, ნიკოლოზ, ニコラ, ニコラウス, ニコラス, ニルス, 尼克斯, 尼古拉斯, 尼古拉耶夫, 尼尔斯, and 니콜라
Dahl, Simonsen, Svendsen, Andersen, Petersen, Pedersen, Jacobsen, Jakobsen, Johansen, Nørgaard, Mogensen, Mortensen, Sørensen, Rasmussen, Henriksen, Kristensen, Jørgensen, Østergaard, Søndergaard, Christensen, Kristiansen, Mikkelsen, Eriksen, Nielsen, Nikolov, Lund, Ller, Holm, Lange, Hoxha, Olsen, Madsen, Rensen, Larsen, Jensen, Jepsen, Hansen, Ivanov, Olesen, Møller, Schmidt, Knudsen, Poulsen, Rgensen, Laursen, Thomsen, Frederiksen, and Christiansen