Q:
Do the Centaurs have a King?
Yes. If you play as a human, you met him in the tutorial, when he summoned the massive earth elemental hands then ran away. You’ll see him again later in an open-world zone called Harathi Hinterlands. Every 3 hours.
No literal king, as he’s a war leader, but they follow Ulgoth. And yes, you do get to fight him as a Champion boss in Harathi Hinterlands’ meta event.
I don’t think they have a single king. There are many different centaur clans with their own leaders, some allied and some not.
If you’re interested the Wiki has a lot of information on centaur culture: http://wiki.guildwars2.com/wiki/Centaur
Ulgoth (who you meet in the human starting instance, and again in Harathi Hinterlands) is the leader of the Modniir tribe, who are the main one Kryta is at war with. They’re allied with the Harathi and some other smaller tribes. But there are others further out who are independent.
“Life’s a journey, not a destination.”