The Nightmare

From Muppet Wiki

This creature was used in The Organized Mind film which premiered on The Mike Douglas Show in 1966. It was one of The Floating Face's scary thoughts.

It also appeared with other monsters in the opening for the first Mike Douglas Show episode of the Muppets' guest week. It surfaced dancing over the closing credits in the final episode of the Muppet guest week too.

The Scary Thought also appeared in an FHA commercial where it was identified as "the Nightmare."

caption by Karen Falk for a Raymond Scott CD

from an FHA commercial

as seen on the cover of TV Guide in 1969

Brian and John Henson dressed for Halloween with an accessory