Jack Jack parr!

Despite being the youngest member of the family, Jack-Jack possesses the greatest variety of superhuman abilities, most of which focus on transformation. Edna Mode classified Jack-Jack as a changeling, comparing his numerous powers to his status as an infant, granting him unlimited potential. Being an infant, he does not yet have full control over his abilities; these are primarily triggered by emotion and whim. It is unknown if Jack-Jack will outgrow most or some of his powers, as this is considered normal for Super-babies. The only other known Super to have retained a large amount of powers past infancy is Meta Man.

Jack-Jack Parr was born around 1961 and was the third child of Robert and Helen Parr.

[When Jack Jack was a baby] Jack-Jack is the deuteragonist of this short film. Bob takes Jack-Jack to Edna so she can study the powers he uses while Bob catches up on some well-deserved rest. Taking Jack-Jack to Edna, she studies different superpowers that he uses to impress her. When Edna is overwhelmed by multiple clones of Jack-Jack, Jack-Jack uses his monster form, combining it with his fire form. Edna later examines Jack-Jack for his powers that he used and gives him a red suit. After studying, Edna takes Jack-Jack to Bob while explaining that whenever she babysits Jack-Jack (unlike other babies), she doesn't charge him while Bob and Jack-Jack go home. At the end of the short, Edna notices Jack-Jack (presumably a clone of himself) by her side, while Edna runs off telling Bob that she forgot her baby.

He has reddish-blond hair and blue eyes. He also has a white smile on the bottom of his mouth. He is 22 years old, although he looks like he's about to turn 17, but he looks young. Although he usually appears in a yellow jumpsuit in the film, he also wears a red super suit with a black mask. When he transforms into a large monster, his skin turns red and he grows sharp fangs and claws that he can use to defend himself and appear intimidating.

Playful, kind, childlike, heroic, self-centered, daring, good-natured, Jack-Jack's emotions are unpredictable; and as these stimulate his powers, being around him when he uses them becomes very difficult to try and calm or restrain him. For example, Jack-Jack loves Mozart's music to the point that he is stimulated by it. He also flies into a rage if he is given a cookie and is not allowed to eat any more. One of the few things that can calm him down is his mother and the rest of his family. Mozart's music prompts him to manifest his powers, which Edna Mode uses to design a new suit with sensors and a wearable monitor that alerts his family of the next use of his powers and allows them to quickly counter them.