Jack-Jack acts like a typical baby. He laughs and giggles a lot but cries whenever he is disturbed. Like many infants, Jack-Jack's emotions are unpredictable; and since his powers are stimulated by them, being with Jack-Jack when the baby uses his powers becomes very difficult when attempting to pacify or restrain him. For instance, Jack-Jack loves Mozart's music to the point where he is stimulated by it. He also becomes enraged if he is given a cookie and is not allowed more. One of the few things that can calm him down is his mother.
He is smart and intuitive for an infant as he recognized Syndrome as an enemy and identified the exploding plane as a danger. He was, in fact, capable of defeating Syndrome single-handed which even the rest of his family combined had failed to do.
Jack-Jack is small, albeit at the average size for a baby as he stands 2'6". He has a single tuft of light brown hair on his head. Although he is usually seen in a yellow onesie during his on-screen appearances in the film, he also has a red super suit with a black mask.
When he transforms into a little monster, Jack-Jack's skin turns red and gains sharp fangs and claws, that he can use to defend himself and look intimidating.
Mozart's music will trigger Jack-Jack into manifesting his powers, which Edna Mode uses to design a new suit that has sensors and a hand-held monitor, which alerts his family to upcoming use of his powers and allows them to counter them quickly. His powers and abilities are significant enough for his siblings to use him as a third member of a rescue team.
Powers and abilities
- Shapeshifting: He can mimic features of other people such as noses and hair. It's unknown if he can affect more than just himself with this ability.
- Monster Form: When upset, Jack-Jack can turn into an aggressive red imp-like form similar to the Hulk, clawing and biting whatever is upsetting him.
- Elemental Mimicry: Jack-Jack has shown the ability to turn himself into different elements. For example, he transformed into a dense solid metal statue.
- Pyrokinesis: When Jack-Jack envelopes himself with fire, he can extend the flame to cover a large area. As demonstrated in the video game LEGO The Incredibles, Jack-Jack is able to project a fiery laser while covered in flames.
- Balloon/Plastic Mimicry: He can become soft and pliable with a visible sheen in order to fend off sharp attacks.
- Molecular Vibration: He can vibrate at an extremely fast rate, dislodging himself out of the arms of enemies or to shake items off.
- Teleportation: He can disappear and mysteriously reappear in another location several feet away.
- Dimensional Travel: He can cross dimensional barriers (labeled 4 on Edna's monitor) and travel through. He can be heard and can hear others through this dimension.
- Intangibility: He can pass through solid objects including force fields with no visible injuries. This is usually accompanied by a blue electric effect.
- Wallcrawling: He can cling to, climb and sit on ceilings and vertical surfaces.
- Enhanced Bite/Matter Ingestion: He can chew and eat his way through the bars of a wooden crib.
- Telekinesis: Jack-Jack can move objects with his mind.
- Levitation: He can lift himself into the air with his mind. It is unknown at this time if this power is self-propelled flight or if he is telekinetic, but he can manipulate the direction he wants to go as well as launch himself in the air to a tremendous height with just a sneeze.
- Laser Vision: He can fire needle thin green lasers (blue in Jack-Jack Attack) from his eyes. These are apparently light-based as they can be reflected easily by a hand mirror.
- Electrokinesis: He can generate electricity.
- Self-Duplication: He can create duplicates of himself.
- Size Manipulation: He can increase his mass and physical size to break through small spaces or crash through walls. While in giant form he is visibly chubbier all over.
- Enhanced Strength/Invulnerability: He is strong enough to physically fight a raccoon and throw lawn furniture. He does this without physical damage as stated by Bob Parr.
Jack-Jack is first introduced being bathed in the sink by his mother, Helen as she talks on the phone to his father, Bob. He is later seen at dinner, with Helen trying to get him to eat his baby food by making funny faces, which he mimics. This also makes his older brother, Dash, feel weird. He laughs when his older siblings, Violet and Dash, get into a fight, enjoying the action and thinking they are playing.
In the montage scene, Jack-Jack is seen being taken care of by Bob, who has recently gained a large amount of confidence, after secretly taking a job on a remote island. He gives him a kiss on the cheek. Realizing that his dad has come to care for him more despite the latter's responsibilities, Jack-Jack giggles. Helen encourages Bob to take a turn feeding Jack-Jack, which he does. Later, Dash and Violet stow aboard a plane Helen had rented, and quickly called Violet's friend, Kari McKeen, to babysit him. The baby is seen playing with an orange ball in his high chair while Kari is talking to Helen on the phone.
He is not seen again until the end of the movie when Syndrome tries to kidnap him to raise him as a sidekick to get revenge on his family. However, thanks to Kari playing Mozart for him, he has learned of his powers and uses them (fire, steel, and demon forms) to escape from Syndrome who is flying up towards his hoverjet. As he is falling towards the ground, Helen catches him. He and the rest of the family are then saved from Syndrome's exploding plane thanks to Violet's force field. Jack-Jack then joins the others in laughter after Dash asks if they will have to move again. At the end of the movie, he is shown clapping for Dash from the bleachers during the track meet and is then shown to be ready to fight The Underminer, thereby setting up the events of the sequel.
In his own mini-movie, we see what happens to him and Kari while the rest of the family is fighting Syndrome. Kari decides to stimulate his cognitive abilities by giving him some educational toys and playing Mozart for him (as she has heard that Mozart makes babies smarter). Listening to the music, he has an epiphany about his powers.
Over the course of the night, he demonstrates many different powers, such as floating through the walls, catching on fire, and shooting laser beams out of his eyes, and Kari tries to keep him and the house in one piece. By morning, Kari has been up all night and figured out how to counter his powers. In her frazzled state of mind, she hands him over to Syndrome, whom she believes to be a replacement babysitter contacted by Helen.
In the sequel, the fight with The Underminer picks up where it left off. Jack-Jack is left in the care of his big siblings. Later, his family is moved into a motel and then into a fabulous new home after his mother gets a new job. While Helen is gone, Jack-Jack reveals to his father that, thanks to Kari, he has awakened at least seventeen of his powers when he fights off a raccoon. Bob is overjoyed but decides to hide this from his family as it could bring Helen home.
Bob leaves Jack-Jack in Edna's care, much to her delight after seeing his powers in action. When Bob picks Jack-Jack up, Edna reveals she upgraded Jack-Jack's suit to help Bob handle him and gives a demonstration. During the demo, Edna reveals that listening to Mozart's music caused Jack-Jack to unleash his powers. When Jack-Jack sees a giant cookie, Bob declares that he must get cookies. Edna tells him that not only does he not need cookies he should not use them with Jack-Jack no matter what he does: Any solution involving cookies will inevitably make him angry enough to not only use his Monster Transformation Power but his Combustion power as well.
- According to official sources, Jack-Jack is 1 year old, is 2'4" (0.71 m) and weighs 30 lbs (13 kg).
- Jack-Jack is not seen or mentioned in the video game and is the only non-playable character of the Parr family in the Disney INFINITY games (he does, however, appear in early concept art for the game, indicating he was likely to appear as an NPC as part of the Incredibles playset before being dropped and is mentioned directly by Helen in her in-game quotes when she is left idle, wondering how Kari is handling him).
- In the comic series, Jack-Jack is a main character but his only used power is that of molecular transformation and appears limited to metal, fire, and monster forms. In the story arc "City of Incredibles", he plays a central role when he gets a cold and inadvertently spreads his transformation powers to others (including his own family), causing their own natural superpowers to be updated to their maximum potential.
- On art and merchandise for the first film, Jack-Jack wears his super suit, but in the film itself, he doesn't at all (except for the very end of the film).
- Jack-Jack has 17 known superpowers, potentially making him the most powerful Super in the Incredibles universe.
- However, he could have just general shape-shifting powers.
- It was planned for Jack-Jack to melt as part of his shape-shifting powers, but this idea wasn't used; it can be assumed that this was due to technical limitations at the time or the fact that it would have seemed too disturbing for younger viewers at the time.
- This limitation appears to have been corrected for the 2018 sequel as seen during his fight against the raccoon.
- Jack-Jack is the only member of his family who doesn't have an "i" emblem on his super-suit.