Kermit the Frog, arguably Jim Henson's most famous Muppet creation, was the star and host of The Muppet Show, played a significant role on Sesame Street, and served as the logo of The Jim Henson Company.
Miss Piggy is a prima-donna pig who is absolutely convinced that she's destined for stardom, and nothing is going to stand in her way.
In The Muppet Movie, Fozzie was the first Muppet Kermit met on his journey. After Fozzie's unsuccessful comedy performance at the El Sleezo Cafe, Kermit invited Fozzie to come to Hollywood with him.