The Muppet Show. When it first started, defining the area of the action with the camera's frame of view instead of the physical set was innovative for a television show. During the late 1970s and early 1980s the show was both aimed at adults and children, while nowadays it has become exclusively a children's show. (Do you really think that WWE's Monday Night Raw would have become such a hit in the late '90s if it hadn't picked up The Muppet Show's "ironic, postmodern backstage drama" gimmick and run to the ends of the earth with it? Same with WCW Monday Nitro. The fact that the Muppets themselves recently repaid the favor by guest-starring on Raw only clenches the argument.)
Even the jokes in the Muppet series from the 1970s and early 1980s can sometimes look very corny and tame.
Sesame Street. Every single children's television show today owes a tremendous debt to this program for blazing the trail. Now that everybody does it, it's hard to remember that Sesame Street INVENTED quality, research-based, curriculum-based, entertaining and educational children's TV that has a visibly ethnically diverse cast and doesn't talk down to its audience.
What makes it even harder to remember all this...is the fact that Sesame Street has pretty much evolved into The Elmo Show.
Spitting Image: The first season hasn't aged very well in terms of puppetry and joke delivery. The makers were still trying to find their style and as a result a lot of early episodes are slow and off the mark. The pilot episode had a laugh track, which was abandoned quickly from the second episode on. Many puppets look lifeless and out of synch, because the puppeteers tried to follow what the actors said live, while from the superior second season on it was decided to have the actors act to a pre-recorded soundtrack, which worked much better. From the second season on puppets also used new techniques that made their eyes blink, which made them appear more alive than in the first season. The voices were more accurate imitations of the celebrities, while from the second season on it was decided to make them more comical and exaggarated to fit with they way they were caricatured, which worked a lot better. Someone who would judge "Spitting Image" from this first season alone would probably wonder how the show ever became such a hit?