What title could I give this fantasy king?

He is one of the leaders of a 'country' that is ruled by two noble families. In essence, he's a king. His brother-in-law is a Duke, and his sons are Princes, but I don't feel calling him 'King' would suit. What other word could I use to describe him, possibly in another language, but a language with the same alphabet as English, so no Russian/Chinese/Arabic etc. His name is Hale Adare btw, thanks!