Dash's superhero power is the ability to run super fast. He is also able to run on water as a consequence of this, as well as other physics-bending maneuvers such as running up buildings.
Being the child of the family, Dash is, as described by Helen, "a highly competitive boy, and a bit of a showoff". Due to society rejecting Supers, he struggles to find a way to vent his energy, not being allowed to partake in sports as it could expose their identities and it would be unfair for other kids. As a result, he took to using his abilities to throw pranks without getting caught to test his limits, causing him to become somewhat of a problem child.
He agrees with his father's belief that he shouldn't be ashamed of his abilities or need to hide them, believing it makes him special. At the same time, he shoots down his mother's claims that "everyone is special", arguing that if that were the case then "no one is".
After the battle against Syndrome and the Omnidroid, perhaps due to his near death experiences, Dash has learned to keep his ego in check. He was allowed to partake in sports under the condition he holds back to give others a chance, a promise he kept.
In Incredibles 2, Dash's personality is more-or-less the same, though he does seem to take school more seriously. He has also developed aspirations of becoming a superhero like his parents.
Dash strongly resembles his father in looks, with the same blond hair, blue eyes and strong jaw. He is also charmingly cute, being a boy at his age.
- Superhuman Speed: Dash's primary superpower is his astonishing superhuman speed, which gives him not only the ability to run superhumanly fast, but also grants him several other abilities that come in handy when in combat or heroic missions. The Incredibles video game shows his maximum speed at over 190 MPH (305Km/h), however, after learning some new abilities while on the heat of battle, Dash realized he was fast enough to run on water and on horizontal surfaces, like walls or ceilings.
- Superhuman Agility: Combining his superhumanly fast speed, with the momentum he creates while on the run, Dash is capable of accomplishing feats of superhuman agility, no other normal human, or even a "Super" like his father, Mr. Incredible, could possibly do.
- Superhuman Reflexes: Dash's speed gives him a superhumanly fast mind and reaction-time, which he uses when engaging in combat or when in the need of improvising. This ability is very much needed when he needs to change direction, while running at superhuman speeds.
- Super-Speeding Combat Ability: Dash's speed affects his entire body, allowing him the ability to combat an opponent with super-speedy punches. However, this does not increase the impact of his blows.
Dashiell is a very rebellious boy and often gets into trouble and loves playing pranks on his least favorite teacher, Mr. Bernie Kropp. He believes that he should use his superpowers; his mother, Helen Parr/Elastigirl, disagrees. His goal is to compete in sports: his power of speed would make him special, give him an unfair advantage and supers have to keep their powers secretive. His mother forbids it on account that "Everyone's special" (which is, as noted by Dash to be the equivalent of saying "No one is").
Dash's charmingly reckless nature and one-track mind always gets him into trouble with his big sister, Violet. In one scene, he teases her about her crush on her classmate, Anthony "Tony" Rydinger. This eventually causes a fight that is broken up once Lucius Best/Frozone, a long-time family friend, rings the doorbell. Dash spits water at Lucius for him to freeze it– a tradition between the two, but after Lucius catches the icicle, Dash whinily mumbles that he likes it when it shatters. After Dash's father, Bob Parr/Mr. Incredible, returns from Nomanisan Island, Dash and Bob are seen playing numerous games including catch (this foreshadows a later event).
When Bob is captured by Syndrome on his return to Nomanisan Island, Helen packs her bags to rescue him after a brief visit with superhero fashion designer, Edna Mode. As she does, Dash sees the suit made for him and puts it on, naming himself The Dash. In their suits, Dash and Violet stow away on the plane Helen has borrowed from a friend. Consequentially, the three are nearly vaporized by an onslaught of Syndrome's missiles. Helen saves their lives by shaping herself into a parachute.
Helen then changes into a lifeboat with Dash serving as the outboard motor– for which Helen praises him upon their arrival at shore. In their camp out (a cave), she warns the children the bad guys they will be facing differ from those on cartoons: these are merciless. Thus, she allows Dash to run as fast as he can. Being rebellious, Dash hates it when Violet is in charge. He and Violet have another verbal disagreement, in which she is concerned Dash thinks this is merely a vacation. She then lets him know otherwise: "Mom and Dad's lives could be in danger, or worse, their marriage." Dash explores the cave and discovers it's actually a rocket exhaust pipe– and it's being used. They escape just in time and see the rocket off into the night sky.
They spend the rest of the night in the jungle, huddling together to keep warm. The next morning, Dash realizes that he was huddled close to his sister, and jumps up and gags in disgust. Just then, he hears a monitor droid (disguised as a wild bird). He wakes Violet to show her the droid, which she finds very suspicious. Their curiosity triggers a deafening alarm of the droids. Later, the two are cornered by three armed Velocipods. Dash, remembering his mother's advice, starts running. Two chase him (while the third engages an invisible Violet). In this episode, Dash discovers just how formidable his superpower really is: he has a superior reaction time, he can deliver rapid-fire punches (but lacks the strength to do any lasting damage), and at full speed he can run on water. At the end this "the Hundred-Mile Dash", he gets cornered by the two Velocipods. He stops on the lagoon's surface and immediately submerges– saving his life as his pursuers collide into each other.
Eventually, Dash returns to Point A just in time to save Violet from the third Velocipod. Violet then encloses them within a force-field to protect them from gunfire. She discovers that she can float inside her force-fields if she generates them in mid-air. Dash proceeds to move the force sphere by running along its inside surface, i.e. a hamster ball. After destroying a couple more Velocipods, they literally run over their parents. After a brief and joyful reunion, the family works as a super-team for the first time.
Syndrome immobilizes them in zero-point energy and describes Operation Kronos: his plan to fraudulently become a superhero. Amidst Bob Parr's apology to Helen, Vi releases the restraints– allowing their escape. There are no jets in the hangar Helen saw during her arrival to Nomanisan Island, but Dash sees a rocket. Unfortunately, Helen has no knowledge on how to fly a rocket. Violet informs her to "just use the coordinates from the last launch." Syndrome's ex-co-worker Mirage, who became an ally of the family after folding her apparent relationship with him, handles that.
Helen holds a van to the rocket as Dash maintains his impatience asking, "Are we there yet?" Upon their landing, Dash and Violet are nearly crushed to death by Syndrome's Omnidroid v.10, but Violet gets knocked unconcious, and Bob saves them. Syndrome loses the remote and, thus, loses control of his Omnidroid. When Mr. Incredible retrieves it, he throws it to Dash who crosses the pond while catching it (garnering amazement from his dad). After the family and Lucius finally secure the remote, Violet and Dash still childishly fight over it until Helen takes. The Omnidroid is destroyed when Bob hurtles one of the robot's claws through the central core.
On their way home, Dash gets excited about how much fun he had during the entire adventure. When they arrive, they stop Syndrome from capturing Jack-Jack. Syndrome is apparently killed when his cape gets snagged in the turbine of his private jet and Violet saves the family from being crushed by plane wreckage, which totals their home. Dash now wonders if they have to move again; to that the answer is yes. When the smoke clears, one of their neighbors, a tricycle-riding young boy named Rusty, is amazed by what happened yelling, "Oh, man… that was totally wicked!"
A few months later, Dash finally gets his chance to participate in track & field, but agrees with his parents that he cannot do anything to compromise the secret of the Incredibles nor grant himself an unfair advantage over the other contestants. Dash restrains himself, running only fast enough to win a silver cup, to which his family cheers. When celebrating Dash's athletic accomplishment, his victory is interrupted by the Underminer. The family dons their costumes and masks showing their re-dedication to fighting crime.
In the sequel, the fight with The Underminer picks up where it left off and conculdes with the Incredibles being arrested for the damages The Underminer caused. Rick Dicker bails them out and escorts them to a motel. The next day, Dash learns that his mother has a new job and that they're moving into a new house. Dash loves his new house and that his father is helping him with his homework. One day, Dash and Bob see a news story about how a rich guy bought the Incredible. Dash is amazed his father used to drive such an amazing car while Bob is furious since he was told it had been destroyed. Dash is disappointed that his father restrains himself. His disappointment increases when his baby brother Jack-Jack reveals that he has powers and Bob reveals that he knew all along until Bob rants about how overwhelmed he is. That's when Violet and Dash decided to call Lucius for help. The following night, they are attacked by Evelyn Deaver's mind controlled Supers. Dash enables them to escape in the Incredibile. Dash, Violet, and Jack-Jack sneak on board the DevTech's ship to rescue their parents. After freeing their parents and Lucius from Evelyn's mind control, Dash, Violet, and Jack-Jack help them defeat her and make Supers legal again.
- According to official sources, Dash is 10 years old, is 4'0" (121 cm) and weighs 60 pounds (27 kg).
- Dash is based on speedster superheroes, specifically The Flash from DC Comics and Quicksilver from Marvel Comics.
- Specifically, he could be seen as visually based on the Barry Allen version of the Flash, what with the red costume and blond hair.
- In order to give Dash a realistic out-of-breath voice in certain scenes, director Brad Bird made Spencer Fox run laps around the Pixar studio.
- The speed for which one has to be going to be able to run on water is 30 meters per second, which puts Dash's top speed at just under a tenth of the speed of sound (Mach 0.087).
- Dash was voiced by Spencer Fox in the first film and Huck Milner in the sequel since Spencer's voice changed in the 14 year gap between the two movies.