Elaine I. Duillo was an American painter and illustrator known for her romance fiction book covers. She was inducted into the Society of Illustrators Hall of Fame in 2003.
Elaine studied at the High School of Music and Art in Manhattan, where she met John Duillo, who would also go on to become an adventure illustrator and gallery painter. She graduated from Pratt Institute in Brooklyn. She began her career in 1959 illustrating adventure story magazines and gothic novels.
Duillo is known for her prolific, eye-catching, realism painting for romance paperback covers. Her painting style is one of "characteristically flawless draftsmanship, evocative mood and compositional power", and uses "layer upon layer of transparent acrylic washes to achieve a luminous effect". She is credited not only with breaking through into a male-dominated field in the early 1960s, but with redefining romance art at the end of the 1970s and early 1980s, introducing more men and male nakedness into her cover art, and influencing other illustrators who followed her style. She is also credited with aiding the rise to fame of model Fabio Lanzoni when she began using him as a model, first on the cover illustration for Johanna Lindsey's Hearts Aflame. She has worked for paperback publishers including Ace, Airmont, Avon, Balcourt Art Service, Bantam, Berkley, Crescent, Dell, Fawcett Gold Medal, Lancer, Penguin USA, Playboy Press, Pocket Books, New American Library and Zebra Kensington. She retired from book cover illustration in early 2003.