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."
Dash Parr
In the 2018 sequel "Incredibles 2", Dash is having trouble with math and approaches Bob for help which Bob only got frustrated with. Later that night, Bob wakes up and goes through the math book on his own. He wakes up Dash early in the morning to help him finish his homework. Bob later takes Dash and his siblings to the fast food chain "The Happy Platter" to reconnect Violet and Tony which Violet snorted water and made a run for it. Later Dash saw the Incredimoble on TV that just got bought. Angering Bob he went and got the remote to control the Incredimobile which got Dash interested in it and wanted to fire rockets off the Incredimobile which causes a disagreement between Dash and Bob. While they fight over the remote Jack-Jack made his powers known surprising Violet and Dash. When they're in trouble, Dash calls for the Incredimobile which comes and saves them from the mind-controlled superheroes. He, Violet, and Jack-Jack use the vehicle to escape and to get them to the boat where Bob, Helen, and Lucius are being kept prisoners. Violet, Dash, and Jack-Jack are able to free their parents and Lucius after fighting their way through a bunch of supers. Together they manage to stop the boat from crashing into the city and causing more destruction. At the end of the movie Dash accompanied his family to drop Violet and Tony off on their date at the movies. However, after seeing a high-speed car chase, Dash Parr and his family went into action.