Mrs. Thompson is Dr. Doofenshmirtz's senile neighbor, as heard in Phineas and Ferb the Movie: Across the 2nd Dimension. She is voiced by the late Doris Roberts. She apparently borrowed sugar from Doofenshmirtz and knows he is divorced. When Dr. Doofenshmirtz was trying to get back into his building so he could shut off the portal that was letting Norm Bots into the Tri-State area, he realized that he left his keys in the other dimension, so he had to call for someone to let him up. He called Mrs. Thompson, and after several tries, Doof exclaimed that he was selling magazines, when Mrs. Thompson let him up.
- The movie left out how Doofenshmirtz fibbed and told Mrs. Thompson he was selling magazines.
- Phineas and Ferb the Movie: Across the 2nd Dimension (Speaking cameo)
- "Perry The Actorpus" (Mentioned only)