Brown's The Lost Symbol is expected to break global sales records
He may have sold more than 80 million copies of The Da Vinci Code but Dan Brown's works are being offloaded to second-hand shops faster than anyone's.
Oxfam named him the "most donated" author at its chain of charity shops.
John Grisham, Ian Rankin, Danielle Steel and Helen Fielding were the other high-profile authors to achieve the dubious honour of making the top five.
But Brown can take comfort in knowing Oxfam's survey also revealed him to be its second most purchased author.
Brown is unlikely to lose any sleep over seeing his previous novels given away, with his next novel The Lost Symbol expected to break global sales records when it is released next month.
After The Da Vinci Code was released in 2003, it became a worldwide phenomenon. It sold 11.7 million copies in the UK and sparked huge interest in Brown's three previous novels.
OXFAM'S MOST DONATED
1. Dan Brown
2. John Grisham
3. Ian Rankin
4. Danielle Steel
5. Helen Fielding
6. Stephen King
7. JK Rowling
8. Catherine Cookson
9. Patricia Cornwell
10. Mills & Boon
Their popularity also spawned two hit movies each starring Tom Hanks as central character, the symbologist Robert Langdon.
Topping the best-seller list at Oxfam's 700 branches was Rankin, known for his hugely popular Inspector Rebus series.
He said: "It's always good for an author to know that their books are popular. With Oxfam, it's also heartening to realise that each book donated and bought is helping such a worthwhile organisation."
Others on the best-seller list included Bernard Cornwell, Stephenie Meyer, Terry Pratchett, Khaled Hosseini and Margaret Atwood.
Oxfam says that its nationwide Bookfest celebrations last month led donations to the charity's shop network to rise by 40%.
Some donations have also proved particularly lucrative recently. A first edition of JRR Tolkien's Lord Of The Rings sold for £800, while a rare print of the sheet music to Don Giovanni raised £750.