Which books would you most certainly find on a well-read person’s bookshelf?

For some time now, I've felt stuck in my (personal, professional, and intellectual) life and perspective. Over the last year, I've made the decision to step out of my comfort zone and travel and read more often. Already, I've felt significant improvement in my mood and outlook. Now I want to explore more books (well known, or not) that have shaped you in meaningful ways.