Alas. I'm afraid I did not even know he was still alive, but he was still writing children's books at 83. Lloyd Alexander wrote "The Chronicles of Prydain," a series of five* books following young farm boy Taran, who goes from Assistant Pig-Keeper to High King. Based in Welsh mythology, they feel epic and down to earth at the same time - the characters have swordfights and cope with magic, but they also bicker among themselves and complain about having to sleep on the ground. They hold up beautifully for adult readers, so I highly recommend trying them out. (Start with "The Book of Three.") Prydain was mapped out in my head before Narnia, before Middle-earth. I wish Mr. Alexander a safe journey to the Summer Country.
His publisher's obit is here.
*There's a sixth book, "The Foundling and Other Tales of Prydain," but I feel this is more of a glorified appendix.