Zmuda is best known as Andy Kaufman's sidekick, co-writer and friend. Zmuda occasionally portrayed Kaufman's Tony Clifton character on stage and for television appearances (It's rumored that it was actually Zmuda playing Clifton when he appeared on Late Night with David Letterman).
In 1986, Zmuda founded Comic Relief, an annual event that raises money to help homeless men, women and children in the United States. The event is televised on HBO, and is hosted by comedians Robin Williams, Billy Crystal and Whoopi Goldberg.
In 1999, Zmuda wrote a book about Kaufman's life, entitled Andy Kaufman Revealed!, which unvieled a lot of the tricks and hoaxes that the two pulled off in front of audiences and television cameras in the 1980s.
Later that year, Milos Forman directed Man On The Moon, the story of Kaufman's life. Zmuda created the "Tony Clifton" make up for the film, and also appeared briefly as "Jack Burns", a stage manager that gets into a brawl on stage during one of Kaufman's Fridays television appearances. Zmuda was also the co-executive producer for the film.