Constantine (voiced by Matt Vogel) is the main antagonist from Muppets Most Wanted. He is the world's most dangerous frog and a doppelgänger of Kermit the Frog, claiming to also be the "world's number one criminal". In the end, his "Number One" reputation is lost, at least in the world. He then becomes the number one criminal of the animal kingdom.
- His Muppet performer, Matt Vogel, is also known for taking over for the late Jerry Nelson, known for Count von Count, Kermit's nephew Robin (Muppets), and others.
- He will become Sora's enemy on Sora's Adventures of Muppets Most Wanted. Also, he will seek revenge on them and even on Sora's Adventure Series.
- He will become Barney's enemy on Barney's Adventures of Muppets Most Wanted.