Peter and the Wolf illustration by Hannah Radenkova. Nice shillouette style type of work, I like how both the boy and the wolf's eyes are locked on each other like preparing for a battle or friendship?
This book cover shows excellent figure ground/negative space. The contours formed by the position of the fox serve as the shape of a boy, I'm assuming "Peter." This empty space also creates a wonderful focal point for the book title to nestle into.
The Chronicles of Ancient Darkness by Michelle Paver. I picked the first one up for at my local library when they were having a sort out of old or tatty books. I was hooked straight away and it remains one of my favorite series of all time.