Jeff "Swampy" Marsh (born December 9, 1960) is an American animator, writer, director, producer, and voice actor associated with several animated television series, most notably as an executive producer and the voice of Major Monogram for Disney's animated series Phineas and Ferb and Milo Murphy's Law, both of which he co-created with Dan Povenmire. Marsh was born in Santa Monica, California, where he grew up with a heavily blended family dynamic. Marsh has been and continues to be a driving force behind several animation projects, working for over six seasons on the animated television series The Simpsons. Marsh continued to work on other animated television series, including King of the Hill and Rocko's Modern Life, before moving to England in 1996.

Filmography

• Agent P Under C — Major Monogram (voice)
• Hey A.J.! — Executive Producer
• Cartoonified! With Phineas and Ferb — Creator
• 2025Spiked — Big Boss Croc / Exterminator (voice)
• Super Happy Magic Forest — Executive Producer
• How Not to Draw — Major Monogram (voice)
• 2020Phineas and Ferb the Movie: Candace Against the Universe — Major Monogram (voice), Executive Producer, Writer
• Pete the Cat — Writer, Creator
• Milo Murphy's Law — Additional Voices (voice), Executive Producer, Story, Creator
• 2014Phineas and Ferb: Star Wars — Major Hologram / Imperial Officer Jeff / Additional Voices
• 2013Phineas and Ferb: Mission Marvel — Francis Major Monogram / Gordon Gutsofanemu / Additional Voices
• 2013Phineas and Ferb: The Perry Files - Animal Agents — Major Monogram (voice)
• 2012Phineas and Ferb: The Daze of Summer — Writer
• 2011Phineas and Ferb the Movie: Across the 2nd Dimension — Major Francis Monogram / Monogram-2 (voice), Sequence Supervisor, Executive Producer, Writer
• Take Two with Phineas and Ferb — Executive Producer, Creator
• Phineas and Ferb — Francis Monogram (voice), Director, Executive Producer, Writer, Story, Creator
• Shadow of the Elves — Director
• Bounty Hamster — (voice)
• Aaagh! It's the Mr. Hell Show! — Josh (voice)
• 1994Looks Can Kill — Associate Producer
• Rocko's Modern Life — Storyboard Artist, Director, Additional Writing
• Untitled Phineas and Ferb Movie — Major Francis Monogram (voice), Writer, Executive Producer

Appearances as themselves (2)

• 2015TV's Funniest Animated Stars: A Paley Center for Media Special — Self
• 2014I Know That Voice — Self