She wrote at least 63 novels.

(And now I'm suddenly hearing Melissa Manchester singing...if you know what I mean. But "Midnight Louie," in Douglas' case, is a cat - "with the wit of Damon Runyon.")

Oddly, I can't find an obit - and even her WEBSITE is confused as to whether she died in 2020 or 2021!

From Wikipedia:

Carole Nelson Douglas (November 5, 1944 – October 20, 2021) was an American writer of sixty novels and many short stories. She has written in many genres, but is best known for two popular mystery series, the Irene Adler Sherlockian suspense novels 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–Saint Paul area. During her time there, she discovered a long, expensive classified advertisement offering a black cat named Midnight Louie 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."

She began writing fiction in the late 1970s. The late director/playwright/novelist Garson Kanin, a pleased interview subject, took her first novel to Doubleday and it sold shortly after. Amberleigh is a post-feminist historical Gothic novel. Douglas has always addressed women's issues in her fiction and preferred mixing genres from contemporary to historical mystery/thriller, romance and women's fiction, and high and urban fantasy.[1]

Douglas lived in north Texas with her husband, Sam Douglas, and adopted cats.[2]

https://carolenelsondouglas.com/

https://www.fantasticfiction.com/d/carole-nelson-douglas/
(book covers)

https://mysteryreadersinc.blogspot.com/2021/10/carole-nelson-douglas-rip.html
(tribute, with descriptions of her work - but someone got her age wrong; she couldn't possibly have been 77 - I think!)

https://karavansara.live/2021/10/23/good-night-miss-nelson-douglas/
(shorter tribute)

https://www.goodreads.com/series/list/9756.Carole_Nelson_Douglas.html

WRITINGS (this may not be a complete list):
"SWORD AND CIRCLET" FANTASY SERIES

Six of Swords, Del Rey Books (New York, NY), 1982.
Exiles of the Rynth, Del Rey Books (New York, NY), 1984.
Keepers of Edanvant, Tor Books (New York, NY), 1987.
Heir of Rengarth, Tor Books (New York, NY), 1988.
Seven of Swords, Tor Books (New York, NY), 1989.

"IRENE ADLER" SERIES

Good Night, Mr. Holmes, Tor Books (New York, NY), 1990, Forge-Tom Doherty Associates (New York, NY), 2009.
Good Morning, Irene, Tor Books (New York, NY), 1991.
Irene at Large, Tor Books (New York, NY), 1992.
Irene's Last Waltz, Forge (New York, NY), 1994.
Chapel Noir, Forge (New York, NY), 2001.
Castle Rouge, Forge (New York, NY), 2002.
Femme Fatale, Forge (New York, NY), 2003.
Spider Dance, Forge (New York, NY), 2004.

"MIDNIGHT LOUIE" MYSTERY SERIES

Catnap, Tor Books (New York, NY), 1992.
Pussyfoot, Tor Books (New York, NY), 1993.
Cat on a Blue Monday, Forge (New York, NY), 1994.
Cat in a Crimson Haze, Forge (New York, NY), 1995.
Cat in a Diamond Dazzle, Forge (New York, NY), 1996.
Cat with an Emerald Eye, Forge (New York, NY), 1996.
Cat in a Flamingo Fedora, Forge (New York, NY), 1997.
Cat in a Golden Garland, Forge (New York, NY), 1997.
Cat on a Hyacinth Hunt, Forge (New York, NY), 1998.
Cat in an Indigo Mood, Forge (New York, NY), 1999.
Cat in a Jeweled Jumpsuit, Forge (New York, NY), 1999.
Cat in a Kiwi Con, Forge (New York, NY), 2000.
Cat in a Leopard Spot, Forge (New York, NY), 2001.
Cat in a Midnight Choir, Forge (New York, NY), 2002.
Cat in a Neon Nightmare, Forge (New York, NY), 2003.
Cat in an Orange Twist, Forge (New York, NY), 2004.
Cat in a Hot Pink Pursuit, Forge (New York, NY), 2005.
Cat in a Quicksilver Caper, Forge (New York, NY), 2006.
Cat in a Red Hot Rage, Forge (New York, NY), 2007.
Cat in a Sapphire Slipper, Forge (New York, NY), 2008.
Cat in a Topaz Tango, Forge (New York, NY), 2009.
Cat in an Ultramarine Scheme, Forge (New York, NY), 2010.
Cat in a Vegas Gold Vendetta, Forge (New York, NY), 2011.

"DELILAH STREET, PARANORMAL INVESTIGATOR" SERIES

Dancing with Werewolves, Juno Books (Rockville, MD), 2007.
Brimstone Kiss, Juno Books (Rockville, MD), 2008.
Vampire Sunrise, Pocket Books (New York, NY), 2009.
Silver Zombie, Pocket Books (New York, NY), 2010.

"CAT AND A PLAYING CARD" SERIES

The Cat and the King of Clubs, Five Star (Unity, ME), 1999.
The Cat and the Queen of Hearts, Five Star (Unity, ME), 1999.
The Cat and the Jack of Spades, Five Star (Unity, ME), 2000.
The Cat and the Jill of Diamonds, Five Star (Unity, ME), 2000.

OTHER

Amberleigh, Jove (New York, NY), 1980.
Fair Wind, Fiery Star, Jove (New York, NY), 1981.
In Her Prime, Ballantine Books (New York, NY), 1982.
Her Own Person, Ballantine Books (New York, NY), 1982.
The Best Man, Ballantine (New York, NY), 1983.
Lady Rogue, Ballantine (New York, NY), 1983.
Probe ("Probe" series), Tor Books (New York, NY), 1985.
Azure Days and Quicksilver Nights, Bantam (New York, NY), 1985.
The Exclusive, Ballantine (New York, NY), 1986.
Counterprobe ("Probe" series), Tor Books (New York, NY), 1988.
Crystal Days and Crystal Nights, two volumes, Bantam (New York, NY), 1990.
Cup of Clay ("Taliswoman" fantasy series),Tor Books (New York, NY), 1991.
Seed upon the Wind ("Taliswoman" fantasy series), Tor Books (New York, NY), 1992.
(Editor) Marilyn: Shades of Blonde, Forge (New York, NY), 1997.
(Editor) Midnight Louie's Pet Detectives, Forge (New York, NY), 1998.
(Editor) White House Pet Detectives: Tales of Crime and Mystery at the White House from a Pet's-eye View, Cumberland House (Nashville, TN), 2002.

https://www.google.com/search?sca_esv=581287324&q=%22carole+nelson%22+douglas&tbm=vid&source=lnms&sa=X&ved=2ahUKEwjpx_OjmbqCAxV8lIkEHSu1D2oQ0pQJegQIDBAB&biw=1920&bih=884&dpr=1
(at least two video interviews)