Dale Carnegie

Dale Carnegie (1888-1955) described himself as a "simple country boy" from Missouri but was also a pioneer of the self-improvement genre. Since the 1936 publication of his first book, How to Win Friends and Influence People, he has touched millions of readers and his classic works continue to impact lives to this day. Image by Dale Carnegie Created in vector format by Scewing (Heritage Auctions) [Public domain], via Wikimedia Commons