The Lion, the Witch, and the Wardrobe
The Professor is a kind old man who owns a large house in the country, to which Peter, Susan, Edmund, and Lucy are sent when they are evacuated from London. The Professor is extremely logical and reminds Peter and Susan not to judge Lucy's story of a magical world called Narnia too harshly, since it's always possible that it is true. When the four children recount their adventures to him, he believes them, and hints that he has personal experience of other worlds, too. We learn much more about the Professor's background, including that his name is Digory Kirke, in The Magician's Nephew. It's tempting to read the Professor as a stand-in for C.S. Lewis himself. Like Lewis, he is a learned and kind-hearted scholar. Also like Lewis, he values and respects the experience of children more than most adults do.