Whatnots are blank Muppet heads, onto which facial features, bodies, and clothes are added to make any kind of character in the Muppet Show universe. A similar group of Muppets known as Anything Muppets appear on Sesame Street.
There were many different Whatnots. In the first two seasons, the Whatnots were mostly shaped like Fraggles. Later in the series, more humanoid Whatnots were added, often with sculpted noses.
In 1993, Playskool released a series of toy Muppet Workshop Puppet Kits based on the concept of Whatnot Muppets.
More recently, The Muppet Whatnot Workshop is an interactive puppet creation display at FAO Schwarz in New York City, and online. For promotion of the workshop, the Muppets (led by the Whatnots) took over the Today Show on November 13, 2008.