Question: What American self-help author sold over 100 million copies of his book Think and grow Rich worldwide by 2015 after his death in 1970?

Context paragraphs:
Mark Manson: Mark Manson (born March 9, 1984) is an American self-help author, blogger and entrepreneur.  He is the author of the website MarkManson.net and two books, "The Subtle Art of Not Giving a F*ck: A Counterintuitive Approach to Living the Good Life", and "Models: Attract Women through Honesty".  He is also the CEO and founder of Infinity Squared Media LLC.

Debbie Ford: Debbie Ford (October 1, 1955 – February 17, 2013) was an American self-help author, coach, lecturer and teacher, most known for New York Times best-selling book, "The Dark Side of the Light Chasers" (1998), which aimed to help readers overcome their shadow side with the help of modern psychology and spiritual practices.  In following years, she went on to write eight more books including "Spiritual Divorce", "Why Good People Do Bad Things", and "The 21-Day Consciousness Cleanse", which have sold over 1 million copies and been translated into 32 languages.  She led workshops on "Shadow Process" and hosted TV and radio shows, and also established the "Ford Institute for Transformational Training".

Codependent No More: Codependent No More is the debut book of self-help author Melody Beattie.  It was originally published in 1986 by the publishing division of the Hazelden Foundation, and became a phenomenon of the self-help movement, going on to sell over eight million copies, six million copies of them in the United States.

Susan M. Campbell: Susan M. Campbell, Ph.D. (born July 16, 1941) is an American self-help author.

Lucinda Bassett: Lucinda Bassett (born February 28, 1956) is an American self-help author and motivational speaker.  Her book "From Panic to Power: Proven Techniques to Calm Your Anxieties, Conquer Your Fears, and Put You in Control of Your Life" is an international bestseller and has been translated into several languages.

Alan Roger Currie: Alan Roger Currie (born March 3, 1963) is an American self-help author, motivational speaker and YouTube personality who has written advice books on dating and interpersonal relationships, verbal communication skills, identifying various manipulative 'mind games' employed between the genders, seduction, erotic dominance & submission (BDSM), and engaging in erotically explicit "dirty talk" with women.

Napoleon Hill: Oliver Napoleon Hill (born October 26, 1883 – November 8, 1970) was an American self-help author.  He is well known for his book "Think and Grow Rich" (1937) which is among the top 10 best selling self-help books of all time.  Hill's works insisted that fervid expectations are essential to improving one's life.  Most of his books were promoted as expounding principles to achieve "success".

Steve Pavlina: Steve Pavlina (born April 14, 1971) is an American self-help author, motivational speaker and entrepreneur.  He is the author of the web site stevepavlina.com and the book "Personal Development for Smart People".

Edmund Bourne: Edmund J. Bourne, PH.D. is an American self-help author, psychologist and researcher on anxiety, anxiety disorders and the treatment of anxiety disorders.  He was the director of The Anxiety and Treatment Center in San Jose and Santa Rosa, California.  In 1990, Edmund Bourne published "The Anxiety and Phobia Workbook", a self-help book that won the Benjamin Franklin Book Award for Excellence in Psychology.  This book is now in its 6th Edition.

Think and Grow Rich: Think and Grow Rich was written in 1937 by Napoleon Hill, promoted as a personal development and self-improvement book.  Hill writes that he was inspired by a suggestion from business magnate and later-philanthropist Andrew Carnegie.  While the book's title and much of the text concerns increased income, the author insists that the philosophy taught in the book can help people succeed in any line of work, to do and be anything they can imagine.  First published during the Great Depression, at the time of Hill's death in 1970, "Think and Grow Rich" had sold more than 20 million copies, and by 2015 over 100 million copies had been sold worldwide.  It remains the biggest seller of Napoleon Hill's books. " BusinessWeek" magazine's Best-Seller List ranked it the sixth best-selling paperback business book 70 years after it was published.  "Think and Grow Rich" is listed in John C. Maxwell's "A Lifetime "Must Read" Books List."

Supporting paragraphs: Think and Grow Rich Napoleon Hill
Answer: Napoleon Hill