Jim Henson started making television programs starring his distinctive googly-eyed creations — part puppet, part marionette — in the 1950s. And they were hits.

Jim Henson and his creation, Kermit the Frog, sit in front of a mural by Coulter Watt. Credit: The Jim Henson Company / MoMI

Early versions of Kermit the Frog, Fozzie Bear and Cookie Monster made the rounds as guest stars on variety shows. But Henson’s Muppets were typecast. Although fuzzy and feather-covered, they were, at first, considered entertainment for adults. They even appeared on “Saturday Night Live” in the show’s early days, when John Belushi called them “the mucking fuppets.” But with the success of “Sesame Street” they became known as entertainers for children.

It took Henson years to redefine his creations. It wasn’t until 1976 that the Muppets got a show of their own — one for all ages. But no American network had been willing to take a chance on a half hour show of puppets, so “The Muppet Show” was produced in England.

The last season aired in 1981 and Jim Henson died suddenly in 1990. Today, The Muppets and many of their human performers are still with us. And while they’ve hit the screen many times since — both on television and in movies — no one’s yet managed to crack the code and find the success the Muppets once had.

WATCH: Studio 360 visits the studio of Michael Frith of Jim Henson Productions.

Video of Studio 360 — American Icons: The Muppets

American Icons is made possible by a grant from the National Endowment for the Humanities.

(Originally aired May 24, 2018)