Thor

Thor is the nephew of Mrs. Weaver, next-door neighbor of the Flynn-Fletchers. Thaddeus, Thor and Mandy were visiting their aunt for the weekend. He has an uncanny resemblance to Ferb, except he has a bigger bulk and yellowish-brown hair, and his style of clothing resembles Phineas' t-shirt and low pants.

Like Ferb, he doesn't often speak. Unlike Ferb's brother, Phineas, who treats Ferb as an equal, Thor's brother is the more dominant of the two. This is evidenced by the fact that Thaddeus snaps his fingers and issues the demand of "Gum me!", and Thor hands him a piece of bubblegum. Ferb and Thor both seem to have a foreign heritage (Hence the name).

During his visit to his aunt's, Phineas and Ferb were told by Candace to compete with Thaddeus and Thor to see who could build the biggest and best backyard fort. ("Thaddeus and Thor")