Jeff "Swampy" Marsh is an American animator, writer, and voice actor, best known for his work on the animated television series Phineas and Ferb. He co-created the show alongside Dan Povenmire, which aired on Disney Channel from 2007 to 2015. Marsh's unique style and humor contributed to the show's popularity among children and adults alike. In addition to his work on Phineas and Ferb, Marsh has been involved in various other projects, including Fish Hooks and Milo Murphy's Law. His contributions to animation have earned him recognition in the industry, making him a notable figure in children's entertainment.