The Bible
Sense and Sensibility (Jane Austen)
Little Women (Louisa May Alcott) as a child...
The Little Prince (Antoine de Saint Exupery)
A Wrinkle In Time (Madeleine L'Engle) again as a child...
The Lion, the Witch and the Wardrobe (C.S. Lewis) again as a child...
Mere Christianity (C.S. Lewis)
On Joy (C.S. Lewis)
The Hobbit, The Lord of the Rings trilogy (J.R.R. Tolkein)
The Screwtape Letters (C.S. Lewis)
Pilgrim's Progress (John Bunyan)

That's my short list... but I have to say that everything I read has influenced me in one way or another. It's just that these are the ones that stand out in my mind as having meant a lot to me or clarified my thinking or informed me about universal truths.

Beccy