Thanks all. These are some great suggestions!
Found this list:
http://scbsfm.blogspot.com/2010/09/baby-names-meaning-king.html
:)
Rex means "king" - I have a cousin with that name.
I love the name St. Clair, but it's not popular at all today!
Isaac is the one we are choosing.
What about a name that belonged to a king or a prince?
If you search in google "names that mean king" or "prince" you get some websites with a lot of options including their origin. Good luck!
Ameer means prince
Malak means king
Both names are arabic