Jeff Marx (born September 10, 1970) is a composer and lyricist of musicals. He is best known for creating the Broadway musical Avenue Q with collaborator Robert Lopez. Together, they wrote all the show's 21 songs. Lopez and Marx both write lyrics and they both write music, together, in the same room, at the same time.
The musical's Original Cast Album, on the RCA/Victor label, was nominated for a Grammy Award. To date, it has sold over 150,000 copies.
Lopez and Marx met in the famed BMI Lehman Engel Musical Theater Workshop. Their very first project together, a spec Muppet movie, Kermit, Prince of Denmark, which was very loosely based on Hamlet, won them (as part of a tie) part of the $150,000 Kleban Award.
Marx grew up in Hollywood, Florida. He attended the University of Michigan. He also holds a juris doctor degree from the Benjamin N. Cardozo School of Law and is a member of the New York Bar Association, but he does not practice law or represent himself.
Marx is well known in Broadway circles for his keen judgment, his abrasive sense of humor and his odd habit of heckling shows he dislikes. As a result he is considered a useful (or feared) critic of his colleagues' work. According to Broadway insiders, if you write a show and Marx sits all the way through without muttering snide comments, snorting or loudly farting, your show is in good shape.
Marx has also written the book How To Win A High School Election.
Marx contributed to a musical version of the NBC sitcom Scrubs, an episode that the New York Times reported has "energized a cast and crew that, at a point when most situation comedies are sputtering along or dead, have recently been doing some of their best work." Marx enjoyed working on the show enough that he attributed it as a reason for his move to Los Angeles. In comparing it to his work on Avenue Q, Marx said: “It took us five years to write ‘Avenue .... There were a million readings and previews and staged readings. With this thing, we wrote the songs in a week. They rehearsed for a week. They filmed it in a week, and it was done. It was liberating, and a collaborative effort that created a much more feel-good way of working.” 
- ↑ The New York Times, Diagnosis: Acute Case of Broadway Melodium Tremens, Tuesday, January 16, 2007.
- www.lopezmarx.com, Robert Lopez and Jeff Marx's website
- The Official Avenue Q website
- Avenue Q merchandise: cd, program, posters, etc.
- Internet Broadway Database listing for Jeff Marx
- Internet Broadway Database listing for Avenue Q: personnel, etc.
- Production: Avenue Q - Working in the Theatre Seminar video at American Theatre Wing.org, September 2003
- Marx's high school Wikipedia entry
- How To Win A Highschool Election Online