The children who enter Narnia in The Lion, the Witch and the Wardrobe are the Pevensies.
Peter, Susan, Edmund, and Lucy Pevensie discover the magical land through a wardrobe while staying in the countryside during the Second World War. Their surname identifies them as siblings and distinguishes them from other child characters in the Narnia series. Lucy is the first to enter Narnia, followed by the others as the story develops.
The Pevensies appear in several Chronicles of Narnia books, although not every sibling has an equally large role in every volume. Eustace Scrubb belongs to a different family and becomes important in The Voyage of the Dawn Treader. Digory Kirke is the professor who owns the house in the first story, while Ransom is the surname of the protagonist in Lewis’s space trilogy. These names are sometimes mixed up because all belong to Lewis’s fictional worlds.