Rudolph the Red-Nosed Reindeer originated in a free booklet first given to children in 1939 by the Montgomery Ward department store chain. Written by Robert L. May, a store copywriter, the story replaced coloring books that had been handed out in previous years. More than 2.3 million copies were distributed in 1939. The more-familiar 1949 song and 1964 animated cartoon differed significantly from the original.
See the whole story at www.history.com/news/rudolph-the-red-nosed-reindeer-turns-75 .