Carole Nelson Douglas (born November 5, 1944) is an American writer. She is best known for two popular mystery series, the Irene Adler mysteries and the Midnight Louie mystery series.
Douglas was a theater and English literature major in college. After graduation, she worked as a newspaper reporter and then editor in the Minneapolis-St. Paul area. During her time there, she discovered a long, expensive classified advertisement offering a black cat named Midnight Louey to the "right" home for one dollar and wrote a feature story on the plucky survival artist, putting it into the cat's point of view. The cat found a country home but its name was revived for her feline PI mystery series many years later. Some of the Midnight Louie series entries include the dedication "For the real and original Midnight Louie. Nine lives were not enough.