In 1999, composers Jeff Marx and Bobby Lopez wrote eight songs and a script treatment for a Muppet feature film called Kermit, Prince of Denmark. Like The Muppet Christmas Carol and Muppet Treasure Island before it, this was a loose adaptation of an earlier work, this time William Shakespeare's play Hamlet.
In the outline, Kermit accidentally travels to Denmark, where he turns out to be the exact double of Prince Hamlet and is frequently mistaken for him. Gonzo and Fozzie were to take on the roles of Rosencrantz and Guildenstern, while Miss Piggy would play both the "lovely Ophelia and the generous Gertrude". Jason Alexander is listed in the treatment as the evil King Claudius. 
The project was conceived as a musical, with Marx and Lopez writing songs for the project as part of their participation in the BMI Workshop, a training ground for many composers, lyricists, and book writers in the musical theater.
Marx and Lopez won the 2000 Kleban Award, a $150,000 endowment to encourage musical theater writers, for the Kermit, Prince of Denmark lyrics. (They tied with four other writing teams and received $37,500 of the total endowment.) The project was sent to the Jim Henson Company, but according to Jeff Marx, "Brian Henson said he wasn't interested, and that was that."
Marx and Lopez went on to write Avenue Q, a musical parody of Sesame Street, which opened on Broadway in 2003, and won three Tony Awards. Marx said that the experience of being rejected by Henson made them determined not to write for other people's characters again.
Marx says that the pair was approached in 2004 by the head of the Muppets Holding Company: "When Disney bought the Muppets, we were approached about making Kermit, Prince of Denmark into a film. Chris Curtin was the Disney guy in charge of the Muppets, and he was the one we were talking to. It looked like it was a "go" -- until Chris left the company, and that was the last we ever heard of the project." 
- Off to Denver
- There's More Than One Pig in the Sea
- Something About Him
- Claudius Rejoices (King For Awhile)
- Without You
- Rosencrantz And Guildenstern Are Doing the Mambo
- Talk (to Each Other)
- In Unexpected Places