Many authors of many nationalities have written about Kings.
English
The author is American
Sammy King, the author of "Penny Arcade," is British. He is known for his contributions to the gaming industry, particularly through his work related to the popular webcomic and gaming culture.
Spanish.
These days, it could be any nationality. But it arose as a surname around 1050 A.D. in Devon, England.
He was the king of Egypt thought to have reigned 610 BC - 595 BC.
Dr. King was a citizan of United States, so American.
Czechoslovakian
Perhaps the title "King of Scotland" which they both held may give you a clue.
Bernard. Joseph has written: 'Nationality, its nature and problems' -- subject(s): Nationalism and nationality
King George III of England was born in England, but his great grandfather (George I) was German.
Nissim Bar-Yaacov has written: 'Dual nationality' -- subject(s): Dual nationality