- See also: "Thaddeus and Thor"
Thor is the nephew of Mrs. Weaver, the next-door neighbor of the Flynn-Fletchers. So far in the series, Thor's first and only appearance, along with his brother Thaddeus, occurs in "Thaddeus and Thor".
Thaddeus, Thor and their older sister Mandy visit their aunt for the weekend. Both Mandy and Candace argue over whose brothers are more annoying and competent. Phineas and Ferb, at Candace's request, agree to compete with Thaddeus and Thor to see who can build the best backyard fort. Thaddeus and Thor build a castle-like fort complete with a slide and a licorice dispenser, which becomes insignificant when compared to Phineas and Ferb's 10-story fort with a swimming pool and a bowling alley.
Thaddeus and Thor's names are patterned after the names of the titular characters, Phineas and Ferb. Thor bears an uncanny resemblance to Ferb, except that he is bulkier than Ferb and has yellowish-brown hair. His style of clothing resembles that of Phineas (T-shirt and low pants), while his brother Thaddeus wears high pants like Ferb.
Not much is revealed about Thor's personality as he is extremely laconic (again, like Ferb). In "Thaddeus and Thor", he does not speak at all.
Unlike Phineas, who treats his brother as an equal, a partner in his projects, the arrogant Thaddeus treats Thor like his sidekick/lackey. When Thaddeus snaps his fingers and orders "Gum me!", Thor hands him a piece of bubblegum. When Phineas tries doing the same to Ferb, he sarcastically replies, "Please!"