Despite fan theories, Dr. Doofenshmirtz as Phineas' biological ... The Phineas and Ferb creator, Dan Povenmire, took to X to ...

Co-creators and exec producers Dan Povenmire and Jeff "Swampy ... Alyson Stoner as Isabella Garcia-Shapiro. Povenmire, of course, voices Dr. Heinz Doofenshmirtz and Marsh is Major Francis Monogram.