Constantine

Constantine, aka the Number One, is the main antagonist of Muppets Most Wanted. He is the world's "Number One" criminal and a doppelgänger of Kermit the Frog, performed by Matt Vogel. Along with his sidekick Dominic (aka "Number Two"), he sets out out to steal an enormous diamond in the film. However, mayhem ensues when he gets entangled with the Muppet troupe on their European tour.

He is almost identical to Kermit aside from a few details. His pupils are shaped like Kermit's, but are slanted in toward each other at a sharper angle. Kermit's signature 11-point collar is duplicated, but Constantine's is notably shorter. The most distinguishable difference is a black mole on Constantine's face that he has covered up. Kermit is seen with it while detained in a Russian prison, having been mistaken for Constantine.

Background
When asked whether he would be playing both the role of himself and Constantine, Kermit replied in the negative (although he did imply that nepotism was involved in casting): "No. We talked about putting me in makeup and having me play both roles, but we decided Constantine needed to be a guy who could do a Russian accent. And, you know, I'm a pretty accomplished actor and all, but besides The Muppet Christmas Carol and Muppet Treasure Island films, I've only really ever played myself. The great thing is, I have like 3,000 relatives back in the swamp, so it was quite easy to find a frog who could play Constantine."

- Kermit

Trivia

 * Constantine is the second main antagonist of a Muppet movie to be a puppet instead of a human, if one counts Miss Piggy's portrayal of the Wicked Witch of the West in The Muppets' Wizard of Oz. In terms of theatrical Muppet movies, he is the first.
 * His collar resembles Young Kermit's from Kermit's Swamp Years.