Who was Jim Henson's first known Muppet "star"?

As noted in the media, Rowlf the Dog is actually considered the first known Muppet "star" of Jim Henson. Rowlf was a recurring character on "The Jimmy Dean Show", which first appeared in a telecast in September 1963. Jim Henson recalled the fact that he thought of creating Rowlf while he was planning the production of a dog food TV commercial for a Canadian show.

Jim Henson (September 1936 - May 1990) as the creator of the Muppets and founder of The Jim Henson Company, was the performer behind many of his company's most loved and famous characters, including Kermit the Frog, Ernie, Dr. Teeth, Rowlf the Dog etc.