For anyone who loves Lord of the Rings or Wizard of Earthsea or Game of Thrones...
The Abhorsen Trilogy beginning with Sabriel. This is a NY Times bestselling series, but I don't hear people talking about it, and it's old enough, you might not know about it for your child who loves fantasy. AND IT HAS A GIRL PROTAGONIST! That is saying something.
Ages 12 and up
Since childhood, Sabriel has lived outside the walls of the Old Kingdom, away from the power of Free Magic, and away from the Dead who refuse to stay dead. But now her father, the Abhorson, is missing, and Sabriel must cross into that world to find him. With Mogget, whose feline form hides a powerful, perhaps malevolent spirit, and Touchstone, a young Charter Mage, Sabriel travels deep into the Old Kingdom. There she confronts an evil that threatens much more than her life and comes face-to-face with her own hidden destiny. . . .