Samuel Benjamin Harris (born April 9, 1967) is an American philosopher, neuroscientist, author, and podcast host. His work touches on a range of topics, including rationality, religion, ethics, free will, determinism, neuroscience, meditation, psychedelics, philosophy of mind, politics, terrorism, and artificial intelligence. Harris came to prominence for his criticism of religion, and he is known as one of the "Four Horsemen" of New Atheism, along with Richard Dawkins, Christopher Hitchens, and Daniel Dennett.

Harris's first book, The End of Faith (2004), won the PEN/Martha Albrand Award for First Nonfiction and remained on The New York Times Best Seller list for 33 weeks. He has since written six additional books: Letter to a Christian Nation (2006); The Moral Landscape: How Science Can Determine Human Values (2010); the essay Lying (2011); the short book Free Will (2012); Waking Up: A Guide to Spirituality Without Religion (2014); and (with British writer Maajid Nawaz) Islam and the Future of Tolerance: A Dialogue (2015). His work has been translated into over 20 languages.

Since September 2013, Harris has hosted the Making Sense podcast (originally titled Waking Up). He also launched a meditation app called Waking Up, promoting secular mindfulness practices. Harris has debated with many prominent figures on religion, including Reza Aslan, David Wolpe, Robert Wright, Rick Warren, William Lane Craig, Jordan Peterson and Deepak Chopra. Some critics have argued that Harris's writings and public statements on Islam are Islamophobic; Harris and his supporters reject that characterization, arguing instead that the label is sometimes used to silence criticism.

Samuel Benjamin Harris was born in Los Angeles, California, on April 9, 1967. He is the son of the late actor Berkeley Harris, who appeared mainly in Western films, and television writer and producer Susan Harris (née Spivak), who created Soap and The Golden Girls, among other series. His father, born in North Carolina, came from a Quaker background, and his mother is Jewish. He was raised by his mother following his parents' divorce when he was age two. Harris has stated that his upbringing was entirely secular and that his parents rarely discussed religion, though he also stated that he was not raised as an atheist.

While his original major was in English, Harris became interested in philosophical questions while at Stanford University after an experience with MDMA. The experience interested him in the idea he might be able to achieve spiritual insights without the use of drugs. Leaving Stanford in his second year, a quarter after his psychoactive experience, he visited India and Nepal, where he studied meditation with teachers of Buddhist and Hindu religions, including Dilgo Khyentse. For a few weeks in the early 1990s, he was a volunteer guard in the security detail of the Dalai Lama.

In 1997, after eleven years overseas, Harris returned to Stanford, completing a B.A. degree in philosophy in 2000. Harris began writing his first book, The End of Faith, immediately after the September 11 attacks.

He received a Ph.D. in cognitive neuroscience in 2009 from the University of California, Los Angeles, using functional magnetic resonance imaging to conduct research into the neural basis of belief, disbelief, and uncertainty. His thesis was titled The Moral Landscape: How Science Could Determine Human Values. His advisor was Mark S. Cohen.

Harris's writing concerns philosophy, neuroscience, and criticism of religion. He came to prominence for his criticism of religion (Islam in particular) and he is described as one of the Four Horsemen of Atheism, along with Richard Dawkins, Christopher Hitchens, and Daniel Dennett. He has written for publications such as The New York Times, the Los Angeles Times, The Economist, The Times (of London), The Boston Globe, and The Atlantic. Five of Harris's books have been New York Times bestsellers, and his writing has been translated into over 20 languages. The End of Faith (2004) remained on The New York Times Best Seller list for 33 weeks.