Santa, as most of us envision him, was created by illustrator Haddon Sundblom in the 1930s for Coca-Cola. In 1992 the book Dream of Santa: Haddon Sundblom's Vision was published by Staples & Charles. The book covers the images painted from 1933 to 1964. Included is a nice foreword entitled "Who Is Santa Claus?" followed by a few pages about Haddon Sundblom.
Though I believe the book is out-of-print, for Santa enthusiasts it's well worth tracking down. I have put a link in the left-hand column to copies available at Amazon. You can also visit the following Coca-Cola website for more information about this iconic image: http://www.thecoca-colacompany.com/heritage/cokelore_santa.html