Well I'm going to cheat and mention more than 5 because it's my journal. Also really it depends on what you want out of life. For best results, just read all these books.
My all-time favorite fiction books:
A Wrinkle In Time by Madeleine L'Engle Love breaks down the complicated machinery of oppression because machines just can't deal with the complexity of it all.
Contact by Carl Sagan my favorite book ever, about how the things we search for are physically near to us but conceptually far, so we're not looking in the right places. Much deeper than the movie.
The Screwtape Letters by C.S. Lewis A person doesn't have to run out and murder people for their soul to be destroyed. They can just give up on life. This is a Christian book but I think it applies to lots of religions.
Sherman Alexie's The Absolutely True Diary of a Part-Time Indian
The purpose of books is to let us see the world through somebody else's eyes. This young adult fiction story about a struggling smart kid trying to break free from the cycles of poverty on an indian reservation goes really far down the important road of helping us understand how to help at-risk kids.
My all-time favorite non-fiction books:
Innumeracy Because it's funny, charming, gives you great ways where we need to apply more math, and is basically a celebration of thinking.
Half the Sky: Turning Oppression into Opportunity for Women Worldwide I didn't read this book for a long time because I thought it'd be too depressing to read about women's lives around the world in countries where women are treated terribly. But the book has so many stories about badass women who overcame the odds, I felt uplifted and hopeful. If we can keep going the right direction the world can be a wonderful place.
Myths of Innovation There are too many stories about science being done by a single lone genius who randomly gets an idea and *bam*, there's the iphone. Kids grow up thinking if I'm not that genius by age 7, why even go into science. This book was an inspiration, it reminded me that there's a place for everyone in science and innovation, it's just that history glosses over the real stories in the interest of oversimplification. Also the author is a cool dude.
Must read if you work at a job: Switch - How To Change When Change Is Hard Contrary to what you see at work, changing people's minds does not start with an inspirational photo on the company intranet. This book breaks down real leadership into usable nuggets that involve reading people, responding, making tiny strides, and bringing others with you along a path to a clear destination.
Must read if you want to save money: All Your Worth by Elizabeth Warren - after disliking Dave Ramsey, not relating perfectly well to Rich Dad Poor Dad, and finding interesting but not terribly usable advice in The Millionaire Next Door, Elizabeth Warren's book on personal finance hit me with all the right advice and became my personal financial planning handbook forever.
Must read for parents: Unconditional Parenting: Moving from Rewards and Punishments to Love and Reason by Alfie Kohn The parenting version of "Switch" about how kids will learn to think for themselves if you treat them like people and take them along with you in logical reasoning, instead of resorting to the carrots and sticks of sticker charts and punishments. You wouldn't turn an adult relationship into an economic system where involved parties try to nickle and dime each other, don't turn your parenting into one either.
And finally, must reads for feminists, which go to a whole different category:
1) Lean In
2) Backlash by Susan Faludi
3) Ain't I a Woman by Bell Hooks
4) She Wins, You Win by Gail Evans
5) Perfect Madness: Motherhood in the Age of Anxiety by Judith Warner
That should do it for now. Sorry for totally cheating. I really did cut down this list, then just gave up.