What is the name of the prince in Prince Caspian?

The prince in Prince Caspian is named Caspian.

Prince Caspian is the rightful heir to the Narnian throne and the central human character of C. S. Lewis’s second-published Narnia novel. His uncle, Miraz, has seized power after killing Caspian’s father, King Caspian IX. When Miraz’s own son is born, Caspian becomes an even greater threat to the usurper.

The four Pevensie children return to Narnia to help Caspian restore the old order. Only about a year has passed on Earth, but roughly 1,300 years have passed in Narnia. During that time, the Telmarines have conquered the land and pushed many talking animals and ancient Narnians into hiding.

The other options are names from elsewhere in the series. Tirian is the last king of Narnia, Rilian is the prince featured in The Silver Chair, and Corin is a prince of Archenland in The Horse and His Boy. Caspian later becomes King Caspian X and appears again in The Voyage of the Dawn Treader.