Marx (left) and Lopez (right)

Robert Lopez (born February 23, 1975) is a composer and lyricist of musicals. He is best known for creating the Broadway musical Avenue Q with collaborator Jeff Marx. 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.

Avenue Q won the 2004 Tony Award for Best Musical. Lopez/Marx's musical score earned them a 2004 Tony Award. A third 2004 Tony Award was awarded to Avenue Q bookwriter Jeff Whitty.

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.

Avenue Q opened on Broadway July 31, 2003 at the John Golden Theater. It is still running there. Additional productions are planned for Las Vegas and London's West End.

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.

They are currently working on an original movie musical for Universal Pictures, and a stage musical in collaboration with Matt Stone and Trey Parker, creators of South Park.

His musical version of Finding Nemo, written in collaboration with his wife, Kristen Anderson-Lopez, will open at Walt Disney World's Animal Kingdom Park in November 2006.

He also collaborated with his brother, the NYC musician & poet Billy Lopez, on several episodes of Nickelodeon's hit series, The Wonder Pets.

Lopez grew up in the Greenwich Village neighborhood of New York City. He attended Hunter College High School and received a B.A. in English from Yale University. He lives in Manhattan with his wife and their new daughter Katie (born March 25, 2005).