Drvan, Nepoznati knez, Višeslav, Rdoslav, Prosigoj, Vlastimir they were Serbian monarchs and not Christians.
Mutimir, Pribislav, Petar, Pavle, Zaharija, Časlav, Jovan Vladimir, Stefan Vojislav, Vukan, Uroš I, Uroš II, Beloš, Desa, Tihomir, Stefan Nemanja, Knez Lazar, they were Serbian monarchs and Christains but not crowned, as well all modern except Petar I.
Not to mention non-Christian Monarchs (far more numerous than Christain). Monarchy is a form of government in which sovereignty is actually or nominally embodied in a single individual, usualy hereditary in certain family.
That one is even worst.