Peter Cratchit is the frog son of Bob and Emily Cratchit in The Muppet Christmas Carol. His siblings are Betina and Belinda Cratchit and Tiny Tim Cratchit. Peter takes after his father, and tends to be brushed to the side by his more forceful sisters.
Behind the Scenes
According to the back cover of the 1993 storybook A Merry Muppet Christmas: Through the Window, the role of Peter Cratchit is played by a frog named Simon. In the character commentary on the 2012 Blu-ray release of the film, Rizzo the Rat says Peter's real name is Peter Frog.
Peter Cratchit, in the original A Christmas Carol, is the eldest son of three male Cratchits. He doesn't turn the spit for the goose, but he does prepare the potatoes and later mashes them "with incredible vigor."