Caspian rules the fictional kingdom of Narnia in several books by C.S. Lewis.
Prince Caspian introduces Caspian as the rightful heir to the Narnian throne. He opposes his uncle Miraz, who has seized power, and eventually becomes King Caspian X. Caspian later appears in The Voyage of the Dawn Treader and The Silver Chair, where his reign and family remain important to the story.
Narnia is the central setting of Lewis’s seven-book fantasy series, The Chronicles of Narnia. It includes talking animals, magical beings, and human visitors from our world. Although other lands such as Archenland, Calormen, and Telmar appear in the series, Narnia is the kingdom associated with Caspian’s throne.
The name Narnia is also used for the entire fictional world in casual conversation, though the books distinguish the kingdom of Narnia from the wider world and its neighboring countries.