The Apple Tree Man
In ACircleOfCats, Aunt has an ancient, gnarly apple tree in her orchard-gone-wild, which her family have always called the "Apple Tree Man". Lillian imagines that there's a real man living in the tree and leaves him milk and biscuits for breakfast.
Later in the book she discovers just how right she was, and her kindness is repaid manytimes over.
The Apple Tree Man describes himself as "The old spirit of an old tree."