Which Pevensie sibling is crowned Queen Susan the what?

Queen Susan is crowned Queen Susan the Gentle.

Susan Pevensie is one of the four children who become rulers of Narnia after the defeat of the White Witch. As queen, she shares the throne with Peter, Edmund and Lucy during the kingdom’s celebrated Golden Age. Her title reflects her reputation for compassion, restraint and practical judgment.

Susan is also associated with the title Queen Susan of the Horn. Father Christmas gives her an ivory horn, which can summon aid when it is blown. In Prince Caspian, that horn becomes crucial: Prince Caspian uses it in his desperate struggle against his uncle, Miraz, and its magic ultimately helps bring the Pevensies back to Narnia.

Readers sometimes confuse Susan’s epithet with the titles of her siblings. Peter is the Magnificent, while Edmund is the Just and Lucy is the Valiant. Susan’s canonical title is the Gentle.