Elves are the traditional helpers of Santa Claus in Christmas stories.
The Great Santa Claus Switch
The 1970 special The Great Santa Claus Switch featured a group of elves working in Santa's Workshop. They introduced themselves in the song "Happy Little Christmas Elves" as "Zippity, Skippity, Hoppity, Bing, Bong... and Fred."
Fred, performed by Jim Henson, was the only elf to realize that Santa had been replaced by an evil twin, Cosmo Scam, who was bent on filling the workshop with monstrous Frackles and ruining Christmas.
The other elves were performed by Jerry Nelson (Zippity), Frank Oz (Skippity and Hoppity), Richard Hunt (Bing) and John Lovelady (Bong).
In the 1996 special Elmo Saves Christmas, a group of Anything Muppet elves become increasingly frustrated by the endless Christmas labor caused by Elmo's wish that he could have Christmas every day.
Stiller the Elf met Elmo in the 2007 special Elmo's Christmas Countdown, and the Sesame Street friends helped Stiller track down the numbers for his Christmas counter-downer.
Santa's chief elf (played by Paul Williams) appeared in the 2008 special A Muppets Christmas: Letters to Santa.