Jeff "Swampy" Marsh

Marsh met Dan Povenmire while working on Rocko's Modern Life and continued to work alongside him on Phineas and Ferb.

As an adult, Marsh became a vice president of sales and marketing for a computer company. One day, he "freaked out" and decided to quit. A friend of his helped him put together a portfolio and go into the animation business.[7] He eventually found himself working on the animated television series The Simpsons as a background layout artist in 1990.[8] Marsh worked on the series for over six seasons and three episodes he helped produce won Emmy Awards.[3] To help him with his animation efforts on the show, Marsh utilized several books about art, architecture design, and artistic rendering which he kept in his household library.[9] His desk in the series' office placed him opposite of fellow layout artist Dan Povenmire; the two bonded over shared tastes in humor and music and quickly formed a friendship.[5]

By 1993, Marsh was working as a writer and director on Nickelodeon's animated series Rocko's Modern Life[3]— the channel's first "in house" cartoon production[10][11][12]— for four seasons.[3] He found himself working alongside Povenmire again, this time as a writing partner,[5] a choice Marsh claimed was made by the crew in hopes of making Povenmire's neatness offset his own sloppy storyboarding.[7] The pair developed a distinctive style, including in their stories' characteristic musical numbers and chase scenes.[13] Together they won an Environmental Achievement Award for a 1996 Rocko episode they had written.[3][14]

In 1996, Povenmire and Marsh conceived the series Phineas and Ferb,[15] based on their similar experiences of childhood summers spent outdoors. Povenmire went through several unsuccessful pitches to get the series picked up.[5] In 1997, Marsh was hired as one of the first artists for the Fox Network animated series King of the Hill,[16] serving as both a storyboard artist and designer.[3]

After working on Rocko in 1996, Marsh moved to London, England, which he considered to be "absolutely fantastic."[17] Marsh spent six years in the city,[3] working on several animated television productions which included Legend of the Dragon, Postman Pat and Bounty Hamster,[17] along with other projects produced by major companies BBC, ITV, and Carlton TV.[3] He also served as a large contributor and producer for several British feature films, working for BKN International subsidiary BKN New Media Ltd.[3]

Around 2005, Povenmire contacted Marsh, notifying him that a pitch for Phineas and Ferb had been somewhat successful and The Walt Disney Company had shown interest in producing the series but wanted to see an eleven-minute pilot.[13][18] Marsh immediately accepted and began packing.[17] He had already booked a vacation to Los Angeles, while Povenmire had plans to travel to France; while Povenmire set up a sidetrack to travel to England, Marsh flew down to Los Angeles for two days where he devised a plot outline for the episode "Rollercoaster". When Povenmire went to France, he drew the storyboards and plotted out how it would all come together, and then went to England where the pair touched up the dialogue and checked to make sure it came out how they had planned it.[18]

Marsh moved back to the United States when Disney accepted the pilot episode and ordered a full 26-episode season.[13][17] The pair still needed to convince overseas Disney executives to pick up the series, so instead of a conventional script, they recorded the storyboards for "Rollercoaster". Povenmire then spent time dubbing over it with his voice for each character, along with sound effects and narration. When the recording was sent to the executives, they accepted and the series was officially greenlit for the company's cable network Disney Channel.[14][19] It officially began broadcast on February 1, 2008, and the cartoon was named Phineas and Ferb.[20][21]

Marsh and Povenmire wanted to incorporate into the show the kind of humor they had developed in their work on Rocko's Modern Life. They included action sequences and, with Disney's encouragement, featured musical numbers in every episode after "Flop Starz".[13] Povenmire described the songs as his and Marsh's "jab at immortality",[15] but the pair have earned two Emmy nominations for Phineas and Ferb songs to-date.[7] A third Emmy nomination, for the episode "The Monster of Phineas-n-Ferbenstein" (2008),[22] pitted the show against SpongeBob SquarePants,[23] although neither nominee received the award due to an unspecified technicality.[24]

The distinctive style of Tex Avery influenced the show's artistic look, which includes geometric shapes in both the characters and the background. The style was determined by Povenmire's first sketch of title character Phineas Flynn, who he doodled on the butcher paper covering the table during dinner with his family in a restaurant in South Pasadena, California; he was so taken with the sketch he tore it out, kept it, and used it as the prototype for Phineas and the stylistic blueprint for the whole show.[17] Other than being an executive producer and co-creator, Marsh voices the character of Major Francis Monogram.[3][25] Marsh based his performance of the character on broadcast journalist and anchorman Walter Cronkite.[26]

The final episode of Phineas and Ferb's fourth season aired on June 12, 2015, ending its original run on television.[27] Marsh and Povenmire collaborated again and produced a series for Disney XD titled Milo Murphy's Law, which premiered on October 3, 2016. Two seasons aired and the last episode premiered on May 18, 2019, with later episodes airing only on Disney Channel.[28] Marsh has also developed an animated TV series for Amazon Prime based on the Pete the Cat children's book series, with the first season premiering in September 2018.[29] His recent work includes Phineas and Ferb the Movie: Candace Against the Universe, which was released on Disney+ on August 28, 2020.[27] Currently, he is serving as Executive Producer on the upcoming Disney Junior animated series Hey AJ. [30] On March 16, 2023, it was announced that Marsh would be returning as executive producer and voice director for the upcoming Phineas and Ferb revival.[31]