Betty Boop made her first appearance on August 9, 1930 in the cartoon Dizzy Dishes, the sixth installment in Fleischer's Talkartoon series.
The character was modeled after a combination of Helen Kane, the famous popular singer of the 1920s and contract player at Paramount Pictures (the studio that distributed Fleischer's cartoons), and Clara Bow, who was a popular actress in the 1920s who had not managed to survive the transition to sound because of her strong Brooklyn accent which nevertheless became a trademark for Betty.
Source https://en.wikipedia.org/wiki/Betty_Boop.