Pig impostors

Miss Piggy confronts Kermit the Pig

The pigs take over the theater in The Muppet Show with Cloris Leachman, kidnapping and replacing all of the non-pigs.

Character	Performer	Description
Kermit the Pig Performer: Dave Goelz	Kermit the Frog	Kermit the Pig is a green pig with features similar to Kermit the Frog's, including a collar and ping pong ball eyes. Kermit the Pig takes over as the show's MC, and claims to be a frog. When guest star Cloris Leachman doesn't believe him, he ribbits for her convincingly. By the end of the show, the real Kermit has taken control of the show again -- but Kermit the Pig shows up in the closing to say goodbye to the audience. Kermit, shocked at seeing his replacement, pushes the pig offstage.
Sweetums Performer: unknown	Sweetums	A pig named Sweetums replaced Sweetums. The puppet was recycled from the Ballerina Pig (albeit dressed in furs).
Fozzie Pig Performer: Jerry Nelson	Fozzie Bear	Fozzie Pig (also refered to as "Fozzie the Pig" by Gonzo) is a pig with a porkpie hat and a pink, polka-dotted bow-tie. The pig replaces Fozzie Bear as the show's comedian. In contrast with Fozzie Bear's signature catchphrase, "Wocka wocka," Fozzie Pig says "hogga hogga."
Unnamed Performer: Frank Oz	The Swedish Chef	A pig chef replaced the Swedish Chef in a skit where he prepared popcorn. In contrast with Swedish Chef's signature catchphrase, "bork, bork," the pig chef says "oink, oink." The Swedish Chef returned the favor by impersonating a pig in Muppet Treasure Island.
Dr. Pig Performer: Richard Hunt	Dr. Bob	Doctor Pig replaces Doctor Bob in the Veterinarian's Hospital sketch. Dubbed the "Vegetarian's Hospital," he was assisted by Nurse Piggy and another pig.
Unnamed Performer: Louise Gold	Nurse Janice	A blonde pig replaced Nurse Janice in the Veterinarian's Hospital sketch, re-named "Vegetarian's Hospital".
Unnamed Performer: Jim Henson	The Newsman	A pig replaces the Newsman in a Muppet News Flash sketch. In his report, he mentions a Dr. Bunsen Honeypig, who was said to have successfully converted a sow's ear into a silk purse and became the object of a massive civil and criminal suit by the wife of Vincent van Gogh Pig.