There's only a few actual monarchies in Thedas. (Let's not count those within city-states that are really nothing more than overglorified mayors.)
- Rivain (which is only nominally a monarchy, though they are a strongly matriarchal society, so this one's possibly the third queen)
- Antiva (more of a plutarchy, but has a monarchy, and culturally they no longer accept female rule as per discussed elsewhere in games and such, even though some of the most important Antivan rulers were queens. So, most likely male.)
- Nevarra (ruled by Markus Pentargist, so, that's a dude)
- Orlais, ruled by Empress Celene obviously
- Ferelden, ruled by Cousland+Alistair/Alistair+Anora/Anora/
- Anderfels, a total possibility.