Thunderhead was a super who was killed using his cape. He was only mentioned by Edna Mode, when discussing to Bob Parr, on why his suit shouldn't have a cape. Mr. Incredible described him as "not the brightest bulb".
Prior to becoming a Super, Thunderhead was a high school dropout, and thus took part in "Stay in School" advertisements to encourage children to remain in school.
As a Super, he was good friends with Mr. Incredible, participating in the NSA's pie eating competition where he came in second place. He also attended the wedding of Mr. Incredible and Elastigirl.
Thunderhead also adopted five children with his roommate Scott before his demise.
He died on November 15, 1958, when his cape snagged on a missile during takeoff after he diverted its course away from a city. This resulted in his death.
Thunderhead was described by Edna Mode as "tall, storm powers, nice man, good with kids." He was indeed known for his caring attitude towards kids, adopting 5 of them alongside his roommate Scott. Apart from this, he was also easily controlled by his emotions.
Thunderhead was also remarkably unintelligent, with Mr. Incredible calling him "not the brightest bulb" and his name itself being a play on a "dunderhead," which is defined as a stupid person. He had the lowest possible intelligence rating on his NSA file
Powers and Abilities
Storm Powers: Thunderhead could harness and control extreme weather conditions through the manipulation of barometric pressure. The weakness of this ability was the requirement for the weather to be cloudy, otherwise his abilities would be rendered useless.