Violet Parr
Screenwriter and director Brad Bird conceived Violet as "a teenage girl who just wants to be invisible". In early drafts of the screenplay, Violet is depicted as an infant as opposed to a teenager, since parents Bob and Helen Parr were originally intended to be introduced as retired superheroes who have just begun to attempt to live normal lives much earlier during the film. Violet is voiced by American author and actress Sarah Vowell, who related that she was offered the role unexpectedly. While beginning to cast the film's main characters, Bird had been listening to the National Public Radio program "This American Life", to which Vowell is a frequent contributor. During one of Vowell's regular appearances on the show, Bird heard her contribute an anecdote about a cannon she had helped her father, a gunsmith, build. Bird wanted to cast Vowell based on her description of the event, deciding that she was "perfect" for the part and immediately calling her to offer her the role. Vowell had already earned a reputation for declining several voice acting jobs prior to "The Incredibles", to the point at which her agent warned Bird, "She's a serious writer and she wouldn't do this, so don't waste your time!" However, Vowell states that she simply avoided pursuing animated roles in general because she was content being a writer and found few animated projects particularly interesting prior to "The Incredibles".
The animators animated a rough test sequence to some of Vowell's dialogue from the radio segment about her father's cannon, in which Violet is depicted being startled by a gun that repeatedly fires in her hands. Despite experiencing some hesitation due having never voiced an animated character before, Vowell accepted the role after receiving an e-mail from the film's producer, agreeing to participate in "The Incredibles" because she believes that Pixar is consistently "the best at what they do", comparing the offer to "if Nelson Mandela showed up asking for your help to fight racism". Additionally, she had also been a long-time fan of Bird's work as a filmmaker. Vowell ultimately decided to accept the role based on a sole image she had been sent of the character: a drawing of Violet surrounded by her schoolmates, all of whom appear to be happy and outgoing apart from Violet herself, who is instead hunched over and hiding behind her long hair. Vowell concluded, "I can be that kid. I was that kid. I love that archetype of the morose, shy, smart-alecky teenage girl."
Kim Possible (character)
Kim is voiced by American actress Christy Carlson Romano, who was only 16 years old when she was first cast as the character. The titular role was originally offered to actress Anneliese van der Pol, who turned it down in favor of co-starring as Chelsea Daniels in the Disney Channel Original Series "That's so Raven". Before being cast as Kim, Romano had already been well-known for starring as Ren Stevens in the Disney Channel sitcom "Even Stevens." The actress was finally introduced to the show's creators by Disney Channel executives after Schooley and McCorkle had already auditioned several people for the role. According to McCorkle, Romano "nailed" her audition, which he described as "just fantastic." Kim was Romano's first voice-acting role. Upon being cast as Kim, Romano immediately identified with the character because they were "both dealing with teenage issues" at the time. During the show's first season, Romano and the rest of the "Kim Possible" cast recorded at different locations. Like her character, Romano also balanced her acting profession with schoolwork, and agreed that they are both confident in their endeavors. Because the actress was enrolled in high school in New York City at the time, she was often required to participate in cast meetings and table reads via telephone; Romano was actually unable to attend her own senior prom because she was working on "Kim Possible". Occasionally, the actress herself would serve as creative inspiration for the writers; one episode in particular, "Blush", was based on the fact that Romano is a shy and easily embarrassed person who tends to "blush at even the slightest compliment/awkward situation." The writers also gave Kim several interests that are similar to Romano's own. Schooley enthused that the actress "add[s] something to [her character] that makes it more than a typical gag-oriented cartoon", crediting both her and co-star Will Friedle, voice of Ron, among reasons fans connected with the characters.