a nation''s ruler or head of state usually by hereditary right

Capetian - a member of the Capetian dynasty
Carolingian / Carlovingian - a member of the Carolingian dynasty
czar / tsar / tzar - a male monarch or emperor (especially of Russia prior to 1917)
Emperor - the male ruler of an empire
king / male monarch - a male sovereign
Merovingian - a member of the Merovingian dynasty
Shah / Shah of Iran - title for the former hereditary monarch of Iran
Hanoverian - any of the British sovereigns belonging to the House of Hanover

    ruler     swayer     head of state     chief of state