I've decided that I only want to link the official art on this page. Part of it is that I wasn't particularly happy with a lot of the AI stuff, but it's also because those links kept disappearing (for some reason). It'll be easier to manage the official stuff. Bear in mind that some of these will be heavy spoilers. Anyway, here it goes!
Protector of the Grove (book one) Cover
Elijah (in book 1)
Shape of the Predator (end of book 1 onward)
Shape of the Guardian (end of book 1)
Whispers of the Wild (book 2) Cover
Carmen (book 2-3)
Shape of the Sky (end of book 3 onward)
Shape of Thorn (book 6 onward)
Yloa (book 6)
Shape of the Master (book 7 onward)
Shape of the Sea (book 8 onward)
Sadie Song (book 8 onward)
Elijah (book 8 onward)