From Muppet Wiki

The Fat Blue Anything Muppet is an overweight, round-headed, blue rod puppet used on Sesame Street.

The name Fat Blue has often been used by fans to refer specifically to Mr. Johnson, Grover's recurring customer in several skits. "Fat Blue" is also the only pattern to be identified in CTW style guides with an adjective as well as a color.

Other popular Muppets made from the Fat Blue pattern are Little Chrissy, Simon Soundman, Professor Hastings and Thomas Twiddlebug.

From the 1979 character style guide	A blank Fat Blue	The Miss Muffet Play
Adam T. Glaser	The Banana King	Ben
Bennett Snerf (monster form)	Bernie the Baker	Big Jeffy
Bruno	Clumsy Dwarf (Dwarf #1)	Dew Drops singer
Dirk	Doc Holiday	Dr. Livingstone
Evil Prime Minister	Fairy Godmother	Farmer Fowler
Fat Blue J Friend	"Fat Cat" performer	Fico
"Five People in My Family" Father	George Washington's Father	Gilbert & Sullivan
The Gonk	Grandmother Happy	Gyros Spiniapolis
Hard Head Henry Harris	Harvey Kneeslapper's Fat Blue victim 1	Harvey Kneeslapper's Fat Blue victim 2
Harvey Kneeslapper's Fat Blue victim 3	Harvey Kneeslapper's Mailman victim	John-Boy
King Peter the Persnickety	Lady Agatha	"Lefty" (no relation)
Lefty's boss	Little Chrissy	Mike (Anything Muppet)
Mr. Ice Cream Cone Man	Mr. Johnson	Mr. Lucky
Newsboy	Nickmatic Keyboardist	The Old Woman Who Lives in a Shoe
Pierre Blue	Pokey the Dwarf	Professor Hastings
The Royal Postman	Simon Soundman	Slap-Happy Sly
The Smartest Person in the Kingdom	A Tarnish Brother	Thomas Twiddlebug
Uncle Louie

Fat Blue Live Hand

A live hand variant also exists, but has been used less frequently.

Al	Billy the Grownup	Captain Donald Cragen Muppet
The Great Fentini	Ferlinghetti Donizetti	Forgetful Jones' mother
Grand High Triangle Lover	Joe Hundred Guy's Butler	King Gerry's Doctor
King Goodheart	King Richard the Chicken-Hearted	King Wasteful V
Mama Countess	Miss Marble	Mrs. Dogooder
Sally Smith	Sam	Stella