Dan Povenmire. Art Department: Phineas und Ferb. Dan Povenmire is an American writer, director, cartoonist, singer and voice actor known for co-creating the Disney cartoons Phineas & Ferb and Milo Murphy's Law alongside Jeff Marsh. He also worked on episodes of Rocko's Modern Life, Family Guy and SpongeBob SquarePants. He voiced Dr. Doofenshmirtz, the enemy of Perry the Platypus and antagonist of Phineas & Ferb.