Daniel Gerhard Brown (born June 22, 1964) is an American writer best known for his thriller novels, particularly the Robert Langdon series Angels & Demons (2000), The Da Vinci Code (2003), The Lost Symbol (2009), Inferno (2013), Origin (2017) and The Secret of Secrets (2025). His novels are treasure hunts that usually take place over a 24-hour period and center on recurring themes of cryptography, art, and conspiracy theories.

Brown's books have been translated into 57 languages and have sold over 200 million copies as of 2012. Three of his works—Angels & Demons, The Da Vinci Code, and Inferno—have been adapted into films, while one, The Lost Symbol, was adapted into a 2021 television series.

The Robert Langdon novels are deeply engaged with Christian themes and historical fiction, and have subsequently generated controversy. Brown states on his website that his books are not anti-Christian and that he is on a "constant spiritual journey" himself. He states that his book The Da Vinci Code is "an entertaining story that promotes spiritual discussion and debate" and suggests that the book may be used "as a positive catalyst for introspection and exploration of our faith."

Daniel Gerhard Brown was born on June 22, 1964, in Exeter, New Hampshire. He has a younger sister, Valerie (born 1968) and brother, Gregory (born 1974). Brown attended Exeter's public schools until the ninth grade. He grew up on the campus of Phillips Exeter Academy, where his father, Richard G. Brown, was a teacher of mathematics and wrote textbooks from 1968 until his retirement in 1997. His mother, Constance (née Gerhard), descended from Pennsylvania Dutch Schwenkfelders, and trained as a church organist and student of sacred music. Brown was raised an Episcopalian, and described his religious evolution in a 2009 interview:

I was raised Episcopalian, and I was very religious as a kid. Then, in eighth or ninth grade, I studied astronomy, cosmology, and the origins of the universe. I remember saying to a minister, "I don't get it. I read a book that said there was an explosion known as the Big Bang, but here it says God created heaven and Earth and the animals in seven days. Which is right?" Unfortunately, the response I got was, "Nice boys don't ask that question." A light went off, and I said, "The Bible doesn't make sense. Science makes much more sense to me." And I just gravitated away from religion.

When asked in the same interview about his then-current religious views, Brown replied:

The irony is that I've really come full circle. The more science I studied, the more I saw that physics becomes metaphysics and numbers become imaginary numbers. The further you go into science, the mushier the ground gets. You start to say, "Oh, there is an order and a spiritual aspect to science."

Brown's interest in secrets and puzzles stems from their presence in his household as a child, where codes and ciphers were the linchpin tying together the mathematics, music, and languages in which his parents worked. The young Brown spent hours working out anagrams and crossword puzzles, and he and his siblings participated in elaborate treasure hunts devised by their father on birthdays and holidays. On Christmas, for example, Brown and his siblings did not find gifts under the tree, but followed a treasure map with codes and clues throughout their house and even around town to find the gifts. Brown's relationship with his father inspired that of Sophie Neveu and Jacques Saunière in The Da Vinci Code, and Chapter 23 of that novel was inspired by one of his childhood treasure hunts.