The Greatest Salesman in the World is a best-selling book by Og Mandino, an author whose books have sold over 50 million copies. It was first published in 1968, and re-issued in 1983 by Bantam. The 128-page book is a classic guide to a philosophy of salesmanship, telling the story of Hafid, a poor camel boy who achieves a life of abundance. A hardcover edition was published by Buccaneer Books in June, 1993.

Actor Matthew McConaughey cited this book as having changed his life.