When performing, Gerson was intimidating even to the other actresses working with her.She was the primary inspiration for Marc Davis when animating Cruella.Betty Lou Gerson, who had previously provided her voice as the narrator of the opening scenes of Cinderella, was inspired by Tallulah Bankhead when voicing Cruella De Vil.This is interesting as it is said that Dodie Smith originally conceived the character as an evil parody of Bankhead.He made specific reference in interview to "one woman I knew who was just a monster.She was tall and thin and talked constantly – you never knew what she was saying, but you couldn't get a word in edgewise".The disheveled style of Cruella's hair was inspired by hairdos seen in magazines between the 1940s and 1960s.
Claws were applied to gloves, and necklaces were made from teeth, to add to the idea that Cruella enjoyed wearing parts of dead animals.
Her physical appearance and general manner was described as some sort of hellish beast or demon, a fact referenced in her name and in a song about her.
In sketches exploring designs for Cruella, Marc Davis experimented with more youthful-looking versions of the character.
Davis also worked from live-action footage of character actress Mary Wickes.
Wickes' angular physique and sophisticated, smooth movements in this reference footage inspired Davis to incorporate these contrasting aspects in Cruella's animation. Davis wanted Cruella to move "like someone you wouldn't like" and thought of people who do not listen to any voice other than their own, and thus dominate a conversation or situation.
Though Milt Kahl initially disliked Marc Davis' caricatured approach to the design and animation of the character (complaining in particular about the size of Cruella's feet), he was very impressed by the final product and, thinking Davis to be a better draughtsman, appears to have become rather jealous of his colleagues success with the character.