With encouragement from Tyler Cowen, here's my list. "Influential" to me means it has changed the way I understand the world. In some cases, that happened fast. In others, slowly as I reread. In some cases, both.
To elaborate on something Tyler eluded to -- in preparing this list my awareness of how much it was people rather than books that influenced me was heightened.
I'm also grouping a few in one because their length was physically limited by technology in a way that makes the group comparable in length to only a portion of others on the list.
- Galatians (what does it mean to be free?), 1 John (what is love?), Job (why evil? why not nihilism?), 1 Samuel (for the stories about David).
- Feynman Lectures, especially the lecture from volume II on principal of least action.
- Conceptual Physics by Hewitt, which I studied over the summer in seventh grade and credit as much as any book for my interest in physics.
- Problematics of Jurisprudence by Posner, which I read the summer before law school. Posner sets the bar for intellectual courage.
- The Common Law by Holmes, which led me to understand law as a complex adaptive system long before I had heard the terms.
- The Intelligent Investor by Benjamin Graham, Zwieg edition, which gave me the theory I needed to understand corporate finance after I had learned how to prepare and read financial statements.
- Buffett's letters to his shareholders as collected by Cunningham, which together with Charlie Munger's almanack (honorable mention) took my understanding of Graham's theory to a point where I could connect it up with mathematical principles I learned studying physics.
- Waddell & Bodek on the Rebirth of American Industry, which awakened me to the way in which accounting rules are responsible for commercial culture.
- The Happiness Hypothesis by Haidt, which gave me a reason to start reading psychology and sociology literature for the first time.
- Creativity by Csikszentmihalyi, which gave me the last few puzzle pieces I needed to connect up the many domains of knowledge I have studied formally and informally (physics, law, economics, psychology, sociology) into an integrated whole.