Who ruledover Narnia?

The Magician originally ruled it, but gave it to a lion, named Aslan.

Aslan ruled it for a while before the White Witch took over.

Then Peter, Susan, Edmund, and Lucy (the two sons of Adam and two daughters of Eve) came into Narnia, discovering it in the wardrobe. When they arrived, they helped to take it from the White Witch and ruled. (Peter became King, Susan Queen, and Edmund and Lucy being Prince and Princess.) They ruled for a long time before leaving (this is a long story, but the time in the wardrobe doesn't count in the real world, they spent years and years ruling over Narnia, into their adult hood, until they leave somehow---it was never confirmed how their hierarchy ended, whether they "died" in Narnia time or just left to go back to the real world.) Anywho, other kings and queens took over (such as Prince Caspian). I should also mention most of these kings and queens came hundreds of Narnia years after the four kids. There is a last King of Narnia (I can't name him at the time...I don't have my books with me, but search The Last Battle, which is the title of the last book). The ending is weird. Enjoy.